Glossary

Plain-language definitions of the terms used across these concepts. Where a term has its own page, follow the link to explore it further.

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Accidental: A sharp (♯) or flat (♭) that raises or lowers a note by a half-step. On a piano, the black keys.
Amplitude: The size of a sound wave, heard as loudness. It is independent of pitch.
Arpeggio: A chord played one note at a time instead of all together.
Augmentation dot: A dot written after a note or rest that adds half its value again: a dotted crotchet lasts a crotchet plus a quaver, or 1½ beats.

Bar (measure): A segment of music holding a fixed number of beats, set by the time signature and marked off by bar lines.
Bar line: The vertical line drawn across the staff to mark the end of one bar and the start of the next.
Beam: A thick bar joining the stems of adjacent quavers or semiquavers into a group, replacing their flags so the beat grouping reads at a glance.
Beat: The steady underlying pulse you tap your foot to - the unit every note value is measured against.

Cadence: A short chord move that resolves to the tonic, such as V to I.
Chord: Three or more notes heard together as a single harmonic unit.
Chord progression: A sequence of chords moving through time, the backbone of a song.
Chord quality: The kind of chord - major, minor, diminished and so on - set by its stacked intervals.
Chords in a key: The chords that belong to a key: the diatonic seven, named with Roman numerals.
Chromatic: A note outside the current key. The opposite of diatonic.
Circle of fifths: The twelve keys arranged in a ring, each a perfect fifth from the next.
Consonance: A combination of notes that sounds settled and at rest.
Crotchet (quarter note): A note lasting one beat in 4/4 - the basic pulse unit. Its matching crotchet rest is one beat of silence.

Diatonic: Belonging to the major scale and its modes: seven notes spread across the octave.
Dissonance: A combination of notes that sounds tense and wants to move.
Dominant: The chord on the fifth degree of a scale: the most tense, pulling back to the tonic.
Dynamics: How loud or soft music is played, and the way that changes over time.

Enharmonic equivalent: Two written names for the same note, such as A♯ and B♭.

Flag: The tail on the stem of a quaver or shorter note; each extra flag halves the value. Flags are replaced by a beam when such notes are grouped.
Frequency: How fast a sound vibrates, measured in hertz. We hear it as pitch.

Key: A tonic note plus the scale and chords built on it: a piece of music’s home.
Key signature: The sharps or flats that define a key, written at the start of the staff.

Leading tone: The seventh degree of a scale, a half-step below the tonic, which pulls up to it.

Major scale: The reference seven-note scale, with the step pattern whole-whole-half-whole-whole-whole-half.
Melody: Notes in sequence: the horizontal relationship between pitches.
Minim (half note): A note lasting two beats: half a semibreve. Its matching minim rest is two beats of silence.
Mode: A scale formed by starting the major scale on a different degree, such as Dorian.

Note: The neutral identity of a pitch, like a single piano key. Its written spelling is a separate idea.
Note head: The round part of a written note. Whether it is filled or open is one of the clues to the note’s value.
Note value: How long a note lasts relative to the beat - shown by its note head, stem and any flags. Each value is half the length of the one before.

Octave: The distance between a note and the next note of the same name, at double the frequency.

Quaver (eighth note): A note lasting half a beat: half a crotchet, often beamed in pairs. Its matching quaver rest is half a beat of silence.

Rest: A measured silence that carries a note value just as a note does, so the beat keeps counting. Every note value has a matching rest of the same length.
Rhythm: The relationship between sounds in time, regardless of pitch.
Root: The note a chord or scale is named from and measured against.

Scale: An ordered ladder of notes spanning an octave, set by a pattern of steps.
Scale degree: A note’s position within a scale, counted from the tonic as 1 to 7.
Semibreve (whole note): The longest common note value, lasting four beats - a full bar of 4/4. Its matching semibreve rest is a whole bar of silence.
Semiquaver (sixteenth note): A note lasting a quarter of a beat: half a quaver. Its matching semiquaver rest is a quarter-beat of silence.
Semitone (half-step): The smallest step in our system: one key to the very next, black or white.
Stem: The vertical line attached to a note head on every value shorter than a semibreve.
Subdominant: The chord on the fourth degree of a scale, establishing movement away from the tonic.

Tie: A curved line joining two notes of the same pitch into one sustained sound spanning their combined values - how a note is held across a bar line.
Timbre: The tone colour that makes a piano and a violin sound different on the same note.
Time signature: The pair of numbers at the start of a piece that sets how many beats are in each bar and which note value gets the beat.
Tonic: The home note of a key: its most stable note and centre of gravity.
Transposition: Moving music to a different key while keeping every interval the same.