akousia
Start here

Glossary

Every term on this site in one list, each with a plain definition and a link to the page that goes deeper. No circular definitions, no words you then have to look up as well.

  • one sentence per term
  • links straight to the page
  • plain language
Hear itCmaj7
C4C5

A

  • Accidental - a sharp, flat or natural sign that raises, lowers or cancels a note for the rest of the bar. See reading music.
  • Aeolian - the mode you get by starting the major scale on its sixth degree. It is the natural minor scale under another name. See Aeolian.
  • Alteration - raising or lowering a note inside a chord, like the b9 in a dominant chord, to add tension. See extensions and alterations.
  • Arpeggio - the notes of a chord played one after the other instead of together.
  • Augmented chord - a major triad with the fifth raised a half step. It sounds stretched and belongs nowhere, which is why it works as a bridge. See augmented.
  • Axis progression - the four chords I, V, vi, IV and every rotation of them. See the axis.

B

  • Bar - one group of beats, marked off by a barline. Four beats in a bar is the most common.
  • Bebop scale - a seven-note scale with one extra chromatic note, so the chord tones land on the beats. See bebop scales.
  • Beat - the pulse you tap your foot to. See pulse, tempo and meter.
  • Blues scale - the minor pentatonic with the flat fifth added. Five notes plus one that bends. See pentatonic and blues.
  • BPM - beats per minute, the number that says how fast the pulse runs.

C

  • Cadence - the two or three chords that end a phrase, and the reason it sounds finished or unfinished. See cadences.
  • Chord - three or more notes sounding together. See chords.
  • Chord symbol - the shorthand above the staff: Cmaj7, Am7, G7sus4. See chord symbols.
  • Chromatic scale - all twelve notes in order, each a half step apart. See the chromatic scale.
  • Circle of fifths - the map that puts the twelve keys in order of how closely they are related. See circle of fifths.
  • Consonance - the impression that two or more notes sit comfortably together. The opposite of dissonance, and a matter of degree, not a rule.

D

  • Diatonic - belonging to the key you are in, without accidentals. The seven chords built on a major scale are the diatonic chords. See diatonic chords.
  • Diminished chord - a minor triad with the fifth lowered a half step. Squeezed and restless. See diminished.
  • Diminished seventh - four notes stacked in minor thirds, all equally far apart, so it can resolve almost anywhere. See diminished seventh.
  • Dissonance - the tension you hear when notes rub against each other. Not a mistake: it is what makes resolution feel like something.
  • Dominant - the fifth degree of the key, and the chord built on it. The chord with the strongest pull back home. See harmonic function.
  • Dominant seventh - a major triad plus a minor seventh. The tritone inside it is what creates the pull. See dominant seventh.
  • Dorian - minor with a raised sixth. Minor, but with a window open. See Dorian.
  • Doo-wop progression - I, vi, IV, V, the loop under a generation of ballads. See doo-wop.
  • Downbeat - the first beat of the bar, the one that feels like a landing.

E

  • Enharmonic - two names for the same pitch, like F sharp and G flat. Same key on the piano, different role in the music.
  • Extension - a note added above the seventh: the ninth, eleventh or thirteenth. See extensions and alterations.

F

  • Fifth - the interval of seven half steps, and the most stable interval after the octave. See perfect fifth.
  • Form - how the sections of a song are put in order: verse, chorus, bridge. See melody and form.
  • Fourth - five half steps. Stable in isolation, unsettled above a bass note. See perfect fourth.
  • Frequency - how many times per second a sound wave repeats, measured in hertz. Doubling it takes you up one octave. See sound and hearing.

G

  • Groove - the feel that comes from where the notes sit against the beat, slightly early or slightly late. See swing, shuffle and groove.

H

  • Half step - the smallest distance in Western music, one key on the piano including the black keys. See minor second.
  • Half-diminished - a diminished triad with a minor seventh on top, written m7b5. Softer than a full diminished seventh, and usually on its way to a dominant. See half-diminished.
  • Harmonic function - the job a chord does in a key: home, away, or pulling back. See harmonic function.
  • Harmonic minor - natural minor with a raised seventh, so the dominant chord gets its pull back. See harmonic minor.
  • Harmony - what happens when notes sound at the same time, and the rules of thumb that follow from it. See harmony.
  • Hypermeter - meter above the bar: bars grouped into fours and eights, the reason a chorus lands where it does. See hypermeter.

I

  • Interval - the distance between two notes, counted in half steps. See intervals.
  • Inversion - the same chord with a different note in the bass. See inversions.
  • Ionian - the major scale, seen as the first of the seven modes. See Ionian.

K

  • Key - the note and scale a piece revolves around, and the set of chords that come with it. See diatonic chords.
  • Key signature - the sharps or flats at the start of the staff that say which key you are in. See reading music.

L

  • Leading tone - the seventh degree of a major scale, a half step under the tonic, pulling toward it. See major seventh.
  • Locrian - the mode with both a flat second and a flat fifth, so the home chord is diminished. Rare, and for a reason. See Locrian.
  • Lydian - major with a raised fourth. Bright, open, slightly floating. See Lydian.

M

  • Major scale - the seven notes almost every other scale is compared against. See major scale.
  • Major seventh chord - a major triad plus a major seventh. It floats and does not need to go anywhere. See major seventh.
  • Major triad - root, major third, fifth. The bright chord. See major.
  • Melodic minor - minor with a raised sixth and seventh on the way up. See melodic minor modes.
  • Meter - how beats are grouped, written as a time signature. See time signatures.
  • Metric modulation - changing tempo by making an existing subdivision the new beat, so the change feels earned. See metric modulation.
  • Minor seventh chord - a minor triad plus a minor seventh. Soft, and everywhere in soul and house. See minor seventh.
  • Minor triad - root, minor third, fifth. The darker sibling of the major triad. See minor.
  • Mixolydian - major with a flat seventh. Major, but without the pull home. See Mixolydian.
  • Modal interchange - borrowing a chord from the parallel major or minor. See modal interchange.
  • Mode - the same set of notes heard from a different starting note, which changes which note feels like home. See modes.
  • Modulation - changing key in the middle of a piece. See harmony.

N

O

  • Octave - twelve half steps, the distance at which a note comes back as itself. See octave.
  • Overtone - the quieter frequencies sounding above a note, and the reason a piano and a guitar playing the same note sound different. See sound and hearing.

P

  • Pedal point - one note held in the bass while the chords above it change. See slash chords and pedal point.
  • Pentatonic scale - five notes, with the two that clash most easily left out. See pentatonic and blues.
  • Phrygian - minor with a flat second, so it leans down from the first step. See Phrygian.
  • Polychord - two triads stacked on top of each other and heard as one sound. See polychords.
  • Polyrhythm - two different groupings running at the same time, like three against four. See polyrhythm and polymeter.
  • Power chord - root and fifth, no third, so it is neither major nor minor. See power chord.
  • Progression - a series of chords in order, and the engine under a song. See progressions.
  • Pulse - the steady underlying beat, whether or not anything plays on it. See pulse, tempo and meter.

R

  • Rest - a measured silence. As much part of the rhythm as a note. See note values and rests.
  • Resolution - the moment tension gives way, usually a dissonant note moving a step to a stable one. See cadences.
  • Root - the note a chord is named after and built from.

S

  • Scale - a set of notes in order, from one note up to the same note an octave higher. See scales.
  • Secondary dominant - a dominant chord that points at a chord other than the tonic. See secondary dominants.
  • Seventh chord - a triad with a fourth note a seventh above the root. See seventh chords.
  • Sixth chord - a major triad with a sixth added. Settled, and older than the major seventh. See sixth.
  • Slash chord - a chord with a specified bass note, written C/E. See slash chords and pedal point.
  • Sus chord - a chord with the third replaced by the second or the fourth, so it leans instead of settling. See sus, add and power chords.
  • Swing - playing pairs of eighth notes long and short instead of evenly. See swing, shuffle and groove.
  • Symmetric scale - a scale built from one repeating interval pattern, like the whole tone or the diminished scale. See symmetric scales.
  • Syncopation - accenting where the beat is not, so the rhythm pulls against the pulse. See syncopation.

T

  • Tempo - how fast the pulse runs, in beats per minute. See pulse, tempo and meter.
  • Third - four half steps for a major third, three for a minor third. The note that decides whether a chord sounds bright or dark. See major third.
  • Time signature - the two numbers that say how many beats are in a bar and which note value counts as one. See time signatures.
  • Tonic - the note and the chord that feel like home in a key. See harmonic function.
  • Triad - a three-note chord: root, third and fifth. See triads.
  • Tritone - six half steps, exactly half an octave. The most unstable interval there is. See tritone.
  • Turnaround - the short chord move at the end of a section that sends you back to the start. See twelve bar blues.

U

  • Unison - two instruments on exactly the same note. Zero half steps apart. See unison.

V

  • Voice leading - moving each note of a chord to the nearest note of the next one, so the change sounds smooth. See voice leading.
  • Voicing - which notes of a chord you play, in which order and in which register. Same chord, different sound. See voicings.

W

  • Whole step - two half steps. The distance between most neighbouring notes in a major scale. See major second.
  • Whole tone scale - six notes, all a whole step apart, with no note that feels like home. See symmetric scales.

Keep going

Everything in music theory

Open music theory
The foundation
How music moves
How you use it
Sound itself
Also in this section

The other sections

Everything on this site sits in one of these, in the order they are meant to be learned.

The building blocks
How music works
In practice