Glossary

The music theory terms that appear in the lessons and the tools, each explained in one or two sentences.

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General terms

Accidental: A sign that changes a note: the sharp (#) raises it a half step, the flat (b) lowers it a half step, and the natural sign cancels both, bringing back the natural note.
Arpeggio: The notes of a chord played one after another, string by string, instead of all at once.
Bar: A group of beats that repeats, with the first beat the strongest. The time signature says how many beats each one has: 4/4 has four, 3/4 has three.
Barre: The index finger laid across several strings at the same fret. It acts as a new nut (the strip of bone at the end of the neck, near the tuning pegs, where the strings rest before running over the frets; Portuguese calls both pestana) and leaves the chord shape free to move along the neck. With the finger on only two or three strings, it is called a partial barre.
Capo: A clamp that holds every string down at one fret. Each fret up raises everything a half step, and the hand's shapes stay the same: the C shape with the capo at fret 2 sounds D.
Chord symbol: The symbol that names a chord: the letter of its root, from A to G, followed by the quality, as in C, Dm, G7 or Bm7(b5). The same letters name the notes: A is Lá, B is Si, C is Dó.
Common tone: A note two neighboring chords have in common. The more notes in common, the smoother (and less surprising) the change between them.
Degree: The position of a note or chord inside a scale or key, numbered 1 to 7 (or in Roman numerals for chords: I, ii, iii...). Degree 1 is the tonic.
Enharmonic: Two names for the same sound, on the same fret of the neck: F# and Gb are enharmonic. Which name to use depends on the context.
Four-note chord: A chord of four notes: the triad plus the seventh, stacked one more third up. The maj7, 7, m7 and m7(b5) chords are four-note chords.
Half step: The smallest distance between two notes in Western music, also called a semitone: one fret on the neck. Two half steps make a whole step.
Harmonic field: The set of seven chords formed by stacking thirds on each degree of a key's scale: the “palette” of chords that naturally belong to that key.
Inversion: A chord with a note other than the root in the bass. With the third in the bass, it is the first inversion; with the fifth, the second. The chord symbol shows the bass after a slash: G/B is G with the third, B, in the bass.
Key: The tonic plus the mode, such as D major: it says which notes and chords belong to the key (diatonic) and which come from outside. Portuguese uses the same word, tom, for the whole step: two half steps, two frets on the neck.
Key signature: The sharps or flats a key uses, written once at the start of the music instead of on each note. C major has none, G major has one sharp (F#) and F major has one flat (Bb).
Leading tone: The 7th note (degree 7) of a major key or of the harmonic minor scale: it sits a half step below the tonic and pulls strongly toward it.
Modulation: Changing key in the middle of the music, so that the ear starts to hear another tonic as the center. What confirms the change is a cadence in the new key.
Offbeat: Playing halfway between two beats, on the “and” of “1 and 2 and”, and not on the beat.
Parallel key: A key with the same tonic and the other mode: C major and C minor are parallel keys. Unlike the relative, the scale changes: the natural minor lowers the 3rd, the 6th and the 7th of the major.
Partial barre: A barre on only two or three strings, with the index finger laid across them at the same fret. The small F uses a partial barre.
Pivot chord: A chord that belongs to both keys of a modulation and serves as a bridge between them: it arrives with one function in the old key and leaves with another in the new key. Em is the iii of C major and the vi of G major.
Pulse: The steady beat behind the music, the one you follow by tapping your foot. The bpm (beats per minute) measures how fast it is: 60 bpm is one beat per second.
Relative minor: The minor key that uses the same seven notes as a major key, centered on its 6th degree, 3 half steps below the tonic: A minor is the relative minor of C major.
Syncopation: A hit that would fall on a beat arrives half a beat early, on the “and” before it, and the beat passes without a hit. It is what gives the feeling of the music pulling forward.
Tension: Two things with the same name. In harmony, it is the feeling of instability that asks for resolution, like that of the V7 before the I. In a chord, the tensions are the notes above the seventh, stacked in more thirds: the 9th, the 11th and the 13th.
Tonic: The note that names the key and the scale, and where the music comes to rest: in D major, D. It is degree 1, and the chord built on it, the I, is also called the tonic.
Triad: A three-note chord (root, third and fifth) stacked in thirds.
Tritone: The distance of six half steps, exactly half the octave. Depending on the spelling, it is an augmented fourth or a diminished fifth. It sounds tense and asks for resolution: between the 3rd and the 7th of the V7, it is what pulls the dominant to the tonic.
Voice leading: The path of each note (voice) of a chord to its note in the next chord. The smaller the total distance the voices travel, the smoother the change sounds.
Voicing: The way the notes of a chord are laid out on the neck: on which strings and in which region. The same chord has several voicings, and the choice changes the register and the movement to the next chord.

Cadences

Authentic cadence: V-I (or V7-I): the V chord resolving to the tonic. The most conclusive cadence in tonal harmony: the leading tone (the 3rd of V) pulls up a half step to the tonic.
Authentic cadence with a minor v: v-i: the dominant of the natural minor key, without the raised leading tone. Less conclusive than V-i, because it lacks the half step that pulls up to the tonic.
Authentic cadence with V7 (harmonic minor): V7-i: the dominant of the minor key with the raised leading tone of the harmonic minor scale. It brings back the conclusive pull of the major authentic cadence inside a minor key.
Cadence with a tritone substitution (bII7-I): bII7-I: in place of the V7, a dominant chord a tritone away, which shares the same two tension notes with it (the 3rd and the 7th, with the roles swapped). The root moves down a half step to the tonic.
Deceptive cadence: V-vi (or V7-vi): the dominant resolves to the relative minor (vi) instead of the expected tonic. It postpones the end of the phrase instead of closing it.
Diatonic chords only: A sequence with none of the recognized cadences: every chord belongs to the harmonic field, but the progression does not form a V-I, IV-I, V-vi or any other identifiable pattern.
Half cadence: Any chord arriving on V (most often IV-V): the phrase ends open, on the dominant itself, like a comma instead of a period.
Minor plagal cadence: iv-I in a major key: the minor iv, borrowed from the parallel minor key, resolves to the major tonic. It is the plagal cadence with a darker color.
Modal cadence: bVII-I in a major key, or IV-i (the major IV) in a minor key: the closing move typical of modal harmony, without the half-step leading tone the authentic cadence uses.
Plagal cadence: IV-I: the IV chord resolving straight to the tonic, with no dominant and no leading tone. Less conclusive than the authentic cadence: it is the “amen” sung at the end of a hymn.
Secondary dominant cadence (authentic): V7/x-x: a secondary dominant resolving, with its own leading tone, to the chord x it prepares (e.g. V7/ii-ii). For a moment, the pull of the authentic cadence makes that chord sound like a tonic.
Secondary dominant cadence (deceptive): V7/x-y: a secondary dominant that prepares one chord but resolves deceptively, to a different chord.
Secondary dominant resolving to ii: V7/ii-ii: the secondary dominant of ii, making that chord sound for a moment like a tonic before the harmony goes on its way.
Secondary dominant resolving to V: V7/V-V: the dominant of the dominant, the most common secondary dominant. It prepares the key's V with even more pull.
Secondary dominant resolving to vi: V7/vi-vi: the secondary dominant of vi, making the relative minor sound for a moment like a tonic before the harmony returns to the original key.

Chord function

Diatonic: A chord made only of notes from the key's scale, with no chromatic alterations or borrowings: the opposite of a secondary dominant or a borrowed chord.
Dominant function: The function of greatest tension in the key (V, and also vii°): it holds the leading tone, the note that pulls up a half step to the tonic.
Minor subdominant: A iv (or iiø7) borrowed from the parallel minor key inside a major key: the same moving-away function as the subdominant, with a darker color.
Passing diminished: A °7 chord that links two neighboring chords with the root rising a half step, like C#°7 between C and Dm. It sounds like a disguised dominant of the next chord: C#°7 holds the notes of an A7(b9) without the A.
Secondary dominant: A dominant chord from outside the key, placed a fifth above a chord that is not the tonic (e.g. V7/ii is the V of ii). It makes that chord sound for a moment like a tonic, before the harmony returns to the original key.
Subdominant function: The function of moving away and preparing (IV, and also ii): it builds an expectation of movement, without the strong tension of the dominant.
Tonic function: The function of rest in the key (I, and also iii and vi, which share two notes with I): where the harmony tends to resolve.
Tritone substitution: Replacing a dominant seventh chord with another whose root is a tritone away (Db7 in place of G7, the bII7). The two share the 3rd and the 7th, with the roles swapped, so they resolve to the same chord, and the root moves down a half step to it.
V of ii: The secondary dominant that resolves to ii, making that chord sound for a moment like a tonic.
V of iii: The secondary dominant that resolves to iii, making that chord sound for a moment like a tonic.
V of IV: The secondary dominant that resolves to IV, making that chord sound for a moment like a tonic.
V of V: The dominant of the dominant, the most common secondary dominant: it prepares the key's V with even more pull before the final cadence.
V of vi: The secondary dominant that resolves to vi, making that chord sound for a moment like a tonic.

Chord quality

Augmented chord: A triad with a major 3rd and an augmented 5th (two major thirds stacked). It sounds ambiguous, with no perfect fifth to lean on (e.g. D+ = D-F#-A#).
Diminished chord: A triad with a minor 3rd and a diminished 5th (two minor thirds stacked). It sounds tense and unstable (e.g. D° = D-F-Ab).
Diminished seventh chord (°7): A diminished triad plus the diminished 7th, which splits the octave into four equal minor thirds (e.g. D°7 = D-F-Ab-Cb).
Dominant ninth chord: A dominant seventh chord plus the 9th (e.g. D9 = D-F#-A-C-E). It keeps the tension of the tritone between the 3rd and the 7th and adds color.
Dominant seventh chord: A major triad plus the minor 7th (e.g. D7 = D-F#-A-C). It holds the tritone between the 3rd and the 7th, which pushes the resolution toward the tonic.
Dominant seventh with a suspended fourth (7sus4): A sus4 plus the minor 7th: the seventh of the dominant chord, without the third that would form the tritone with it (e.g. D7sus4 = D-G-A-C).
Half-diminished seventh chord: A diminished triad plus the minor 7th, written m7(b5) or ø (e.g. Dm7(b5) = D-F-Ab-C). It is the viiø7 of the major key: it has the leading tone and the tritone of the V7 but not the root of the V, so it pulls toward resolution less strongly than the V7.
Major chord: A triad with a major 3rd and a perfect 5th above the root (e.g. D = D-F#-A).
Major ninth chord: A maj7 chord plus the 9th (the 2nd an octave up): a soft color, without the tension of a dominant chord (e.g. Dmaj9 = D-F#-A-C#-E).
Major seventh chord: A major triad plus the major 7th (e.g. Dmaj7 = D-F#-A-C#). It sounds stable and “open”, common on the tonic.
Major sixth (6): A major triad plus the major 6th above the root (e.g. D6 = D-F#-A-B).
Major with an added ninth (add9): A major triad plus the 9th, without the 7th. That is why it is written add9 and not 9 (e.g. Dadd9 = D-F#-A-E).
Minor chord: A triad with a minor 3rd and a perfect 5th above the root (e.g. Dm = D-F-A).
Minor ninth chord: A minor seventh chord plus the 9th (e.g. Dm9 = D-F-A-C-E).
Minor seventh chord: A minor triad plus the minor 7th (e.g. Dm7 = D-F-A-C).
Minor sixth (m6): A minor triad plus the major 6th above the root (e.g. Dm6 = D-F-A-B).
Power chord (5): Just the root and the perfect 5th, with no third: neither major nor minor (e.g. D5 = D-A).
Suspended fourth (sus4): A triad where the perfect 4th takes the place of the 3rd, with the perfect 5th kept. With no third, the chord is neither major nor minor (e.g. Dsus4 = D-G-A).
Suspended second (sus2): A triad where the major 2nd takes the place of the 3rd, with the perfect 5th kept. With no third, the chord is neither major nor minor (e.g. Dsus2 = D-E-A).

Scales

Harmonic minor scale: The natural minor with a raised 7th (the leading tone), which makes an augmented second between the 6th and 7th degrees. It is what gives the major V (and the V7) inside a minor key.
Major pentatonic scale: The major scale without its 4th and 7th degrees, the two notes a half step from a neighbor. Five notes are left, with no half step between them (in C: C, D, E, G and A).
Major scale: The pattern of whole and half steps W-W-H-W-W-W-H from the tonic: the reference against which the other scales and modes are measured.
Minor pentatonic scale: The natural minor scale without its 2nd and 6th degrees: the base of most blues and rock licks and riffs on the guitar.
Natural minor scale: The pattern W-H-W-W-H-W-W from the tonic: the same seven notes as the relative major, starting on its 6th degree.

Modes

Aeolian mode: The natural minor scale (built on degree vi of the major scale): minor 3rd, 6th and 7th.
Dorian mode: A minor scale with a major 6th: it sounds minor, but brighter than the natural minor, which has a minor 6th.
Ionian mode: The major scale's name among the modes (built on degree I of the major scale). Its major 7th sets it apart from Mixolydian, which has a minor 7th.
Locrian mode: The only mode with a diminished 5th (b5) above the tonic: unstable, almost never used as a tonal center.
Lydian mode: A major scale with an augmented 4th (#4) instead of the perfect 4th: it sounds major, and brighter.
Mixolydian mode: A major scale with a minor 7th (b7) instead of the major 7th: the sound of the dominant seventh chord, stretched into a scale.
Phrygian mode: A minor scale with a minor 2nd (b2) right above the tonic: the darkest feature among the minor modes.

Intervals

Augmented fourth (tritone): 6 half steps: it splits the octave exactly in half. Enharmonically the same as the diminished fifth (d5). In the V7 it is the interval between the 3rd and the 7th, the tension that pushes the dominant toward the tonic.
Diminished fifth (tritone): 6 half steps: the same distance in sound as the augmented fourth (A4), spelled differently. It shows up in diminished and half-diminished chords.
Major second: 2 half steps (1 whole step): the distance between most neighboring degrees of a major scale.
Major seventh: 11 half steps: the seventh of a maj7 chord, only a half step below the octave.
Major sixth: 9 half steps from the root.
Major third: 4 half steps: stacked on the root, it gives a chord its major sound.
Minor second: 1 half step: the smallest interval in equal temperament, the distance of one fret on the neck.
Minor seventh: 10 half steps: stacked on the triad, it gives the dominant seventh chord and the minor seventh chord their characteristic color.
Minor sixth: 8 half steps from the root.
Minor third: 3 half steps: stacked on the root, it gives a chord its minor sound.
Octave: 12 half steps, the perfect octave: the same note, higher or lower, its frequency doubled with each octave up. On the same string, it sits 12 frets further along.
Perfect fifth: 7 half steps: the most stable interval after the octave, the base of most triads and of the power chord (5).
Perfect fourth: 5 half steps from the root.
Unison: 0 half steps: the same note, or two strings tuned to the same pitch.

Chord tones and tensions

Eleventh: The 4th an octave above the root, a tension beyond the ninth.
Fifth: Usually perfect; with the root and the third, it completes the triad.
Ninth: The 2nd an octave above the root, stacked as a tension beyond the seventh.
Root: The note that names the chord: the base on which the thirds are stacked.
Seventh: The fourth note, stacked in thirds on the triad. It gives the chord color and movement. It can be major (maj7), minor (7, m7) or diminished (°7).
Third: It decides whether the chord sounds major or minor.
Thirteenth: The 6th an octave above the root, the farthest tension before the stack of thirds repeats.

Modal borrowing

Modal borrowing: Bringing into a key a chord from a parallel key, with the same tonic and another mode, without modulating. The most common case is borrowing from the parallel minor key: in C major, Fm (iv), Ab (bVI) and Bb (bVII) come from C minor.
Parallel major key: The major key with the same tonic as the current minor key. It is a less common source of borrowing, used to brighten a minor key for a moment.
Parallel minor key: The minor key with the same tonic as the current major key (e.g. D major and D minor). It is the most common source of modal borrowing (iv, bVI, bVII).