Music Theory Glossary

Quick definitions for every term covered across our lessons.

A B C D E F G H I K L M N O P Q R S T V W

A

ADSR
Attack, Decay, Sustain, Release — the four stages of an envelope that shape how a sound evolves over time. Learn more →
Aeolian
The sixth mode of the major scale, equivalent to the natural minor scale. Learn more →
Arpeggio
The notes of a chord played one at a time in sequence rather than simultaneously. Learn more →
Arrangement
How instruments and parts are organised across sections to shape a song's texture and energy. Learn more →

B

Band-pass filter
A filter that allows only a band of frequencies through, cutting both highs and lows. Learn more →
Bar
A segment of time defined by a set number of beats — typically 4 beats in common time. Learn more →
Bass line
The lowest melodic part in an arrangement, usually played by bass guitar, synth bass, or sub bass. Learn more →
Beat
A single pulse in music — the unit you tap your foot to. Learn more →
BPM
Beats per minute — a measure of tempo. Higher BPM means faster music. Learn more →
Bridge
A contrasting section that breaks the verse-chorus pattern, usually appearing once. Learn more →
Borrowed chord
A chord taken from a parallel key (e.g. using a minor iv in a major key). Learn more →

C

Cadence
A chord progression that signals the end of a phrase — e.g. V→I (perfect cadence). Learn more →
Chord
Three or more notes sounded together, built by stacking intervals from a root note. Learn more →
Chord progression
A sequence of chords played in order, forming the harmonic backbone of a piece. Learn more →
Chorus
The main repeating section of a song, usually containing the hook. Learn more →
Chromatic
Moving by semitones — using notes outside the current key or scale. Learn more →
Circle of fifths
A diagram showing the relationship between all 12 keys, arranged by ascending perfect fifths. Learn more →
Consonance
A combination of notes that sounds stable and resolved — the opposite of dissonance. Learn more →
Counter-melody
A secondary melody that plays alongside the main melody, adding depth and interest. Learn more →
Cutoff
The frequency point at which a filter begins removing frequencies. Learn more →

D

DAW
Digital Audio Workstation — software for recording, editing, and producing music (e.g. Ableton, Logic, FL Studio). Learn more →
Decay
The second stage of an ADSR envelope — how quickly the sound drops from peak to sustain level. Learn more →
Degree
The position of a note within a scale, written as a Roman numeral (I, ii, iii, IV, etc.). Learn more →
Diatonic
Notes or chords that belong to the current key — staying within the scale. Learn more →
Dissonance
A combination of notes that sounds tense or unstable, creating a need to resolve. Learn more →
Dominant
The fifth degree of a scale (V), which has the strongest pull back to the tonic (I). Learn more →
Dorian
The second mode of the major scale — a minor mode with a raised 6th, common in jazz and funk. Learn more →
Dotted note
A note with a dot after it, extending its duration by half its value. Learn more →
Dynamics
Variations in volume and intensity throughout a piece of music. Learn more →

E

Enharmonic
Two note names for the same pitch — e.g. C# and Db are enharmonic equivalents. Learn more →
Envelope
A shape that controls how a parameter (usually volume) changes over time — typically ADSR. Learn more →

F

Filter
A tool that removes certain frequencies from a sound — low-pass, high-pass, or band-pass. Learn more →
Flat
A symbol (♭) that lowers a note by one semitone. Learn more →
Frequency
How fast a sound wave vibrates, measured in Hz — determines pitch. Learn more →

G

Groove
The rhythmic feel of music — created by subtle timing and velocity variations. Learn more →

H

Half step
The smallest interval in Western music — same as a semitone. Learn more →
Harmonics
Higher-frequency overtones that vibrate above a fundamental note, giving each instrument its unique timbre. Learn more →
Harmony
Notes sounding simultaneously — the vertical dimension of music (as opposed to melody). Learn more →
High-pass filter
A filter that removes low frequencies below a cutoff point, letting highs pass through. Learn more →

I

Interval
The distance between two notes, measured in semitones or by name (minor 3rd, perfect 5th, etc.). Learn more →
Inversion
A chord rearranged so that a note other than the root is the lowest note. Learn more →

K

Key
The set of notes (scale) and home chord (tonic) that a piece of music is based on. Learn more →

L

Layering
Stacking multiple parts or sounds together to create fuller textures. Learn more →
Lead
The most prominent melodic element — a vocal line, synth lead, or guitar riff. Learn more →
LFO
Low Frequency Oscillator — a slow-moving wave used to modulate parameters like pitch, volume, or filter cutoff over time. Learn more →
Locrian
The seventh mode of the major scale — the darkest mode, rarely used due to its diminished tonic. Learn more →
Low-pass filter
A filter that removes high frequencies above a cutoff point, making sounds warmer or more muffled. Learn more →
Lydian
The fourth mode of the major scale — a major mode with a raised 4th, giving a dreamy or bright sound. Learn more →

M

Major scale
A seven-note scale following the pattern W-W-H-W-W-W-H — the foundation of Western music theory. Learn more →
Melody
A sequence of single notes that forms a recognisable musical idea — the part you sing or hum. Learn more →
MIDI
Musical Instrument Digital Interface — a protocol that sends performance instructions (notes, velocity, timing) rather than audio. Learn more →
Minor scale
A seven-note scale following the pattern W-H-W-W-H-W-W (natural minor) — sounds darker than major. Learn more →
Mixolydian
The fifth mode of the major scale — a major mode with a lowered 7th, common in rock and blues. Learn more →
Mode
A scale derived from starting on a different degree of the major scale — each has a unique character. Learn more →
Modulation
Changing from one key to another within a piece of music. Learn more →
Motif
A short musical idea (usually 2-8 notes) that recurs throughout a piece, providing unity. Learn more →

N

Note
A single musical sound with a specific pitch and duration. Learn more →

O

Octave
The interval between a note and the same note 12 semitones higher or lower — they share the same letter name. Learn more →
Overtone
A higher-frequency component of a sound that vibrates above the fundamental, contributing to timbre. Learn more →

P

Pedal point
A sustained or repeated bass note held while chords change above it, creating tension. Learn more →
Pentatonic scale
A five-note scale — major pentatonic removes the 4th and 7th; minor pentatonic removes the 2nd and 6th. Learn more →
Phrygian
The third mode of the major scale — a minor mode with a lowered 2nd, common in metal and flamenco. Learn more →
Pitch
How high or low a sound is, determined by the frequency of its vibration. Learn more →
Polyrhythm
Two or more conflicting rhythmic patterns played simultaneously, e.g. 3 against 2. Learn more →
Progression
A sequence of chords — short for chord progression. Learn more →

Q

Quantisation
Snapping MIDI notes to a timing grid to tighten rhythms — can be full or partial. Learn more →

R

Relative major/minor
A major and minor key that share the same notes but start on different roots (e.g. C major and A minor). Learn more →
Resolution
The moment tension releases into a stable, consonant sound. Learn more →
Rest
A period of silence with a specific duration — as important as the notes themselves. Learn more →
Rhythm
The pattern of durations and accents in music — when notes happen and for how long. Learn more →
Root note
The note a chord or scale is built on and named after. Learn more →

S

Sawtooth wave
A bright waveform containing all harmonics — the most common starting point in subtractive synthesis. Learn more →
Scale
An ordered set of notes within an octave that defines the tonal palette of a piece. Learn more →
Secondary dominant
A dominant chord borrowed from another key to tonicise a chord other than I — e.g. V/V. Learn more →
Semitone
The smallest interval in Western music — the distance between two adjacent keys on a piano. Learn more →
Seventh chord
A four-note chord built by adding a 7th interval above the root to a triad. Learn more →
Sharp
A symbol (#) that raises a note by one semitone. Learn more →
Sine wave
The purest waveform — a single frequency with no overtones. Learn more →
Square wave
A waveform containing odd harmonics only, producing a hollow, clarinet-like tone. Learn more →
Sustain
The third stage of an ADSR envelope — the level held while a note is pressed. Learn more →
Syncopation
Accenting notes on unexpected beats — usually off-beats — to create rhythmic tension and groove. Learn more →

T

Tempo
The speed of music, measured in BPM (beats per minute). Learn more →
Tension
A feeling of instability or anticipation in music, created by dissonance, unresolved chords, or rhythmic displacement. Learn more →
Tie
A curved line connecting two notes of the same pitch, combining their durations into one longer note. Learn more →
Timbre
The tonal quality of a sound — what makes a piano sound different from a guitar playing the same note. Learn more →
Time signature
A notation showing how many beats per bar and which note value gets one beat (e.g. 4/4, 3/4, 6/8). Learn more →
Tonic
The first degree (I) of a scale — the home chord that everything resolves to. Learn more →
Tone
An interval of two semitones — also called a whole step. Learn more →
Transposition
Shifting all notes up or down by the same interval — changing the key while keeping the intervals intact. Learn more →
Triad
A three-note chord built by stacking two intervals of a 3rd above a root note. Learn more →
Triangle wave
A soft waveform with odd harmonics that fade quickly — sits between a sine and square wave. Learn more →
Triplet
Three notes played in the space of two — dividing a beat into thirds instead of halves. Learn more →
Tritone
An interval of 6 semitones — the most dissonant interval, dividing the octave exactly in half. Learn more →

V

Velocity
How hard a MIDI note is played (0-127) — controls dynamics and often affects timbre. Learn more →
Verse
A section that carries the narrative or evolving lyrics, usually with the same melody but different words each time. Learn more →
Voice leading
The technique of moving individual notes between chords as smoothly as possible. Learn more →

W

Walking bass
A bass line that moves stepwise between chord tones, creating a flowing, walking motion — common in jazz. Learn more →
Waveform
The shape of a sound wave — determines its harmonic content and tonal character. Learn more →
Whole step
An interval of two semitones — same as a tone. Learn more →