Music Theory Glossary
Essential music theory terms explained in plain language. Tap a category to jump directly.
🎵Fundamentals12 terms
Note
A single musical sound with a specific pitch and duration. Notes are the basic building blocks of all music and are named using the letters A through G.
Learn more →Interval
The distance in pitch between two notes. Intervals are measured in half steps (semitones) and have names like minor 2nd, major 3rd, perfect 5th, etc.
Learn more →Semitone (Half Step)
The smallest interval in Western music, equal to one fret on guitar or one key on piano. Two semitones make a whole step.
Learn more →Whole Step
An interval equal to two semitones (two frets on guitar or two keys on piano). Major scales are built from a pattern of whole steps and half steps.
Learn more →Octave
The interval between one note and the next note with the same name, 12 semitones higher or lower. Notes an octave apart sound like the same note at different heights.
Learn more →Pitch
How high or low a sound is, determined by the frequency of its vibrations. Higher frequencies produce higher pitches.
Frequency
The number of vibrations per second that produce a sound, measured in Hertz (Hz). A440 (440 Hz) is the standard tuning reference for the note A above middle C.
Enharmonic
Two note names that sound the same pitch but are written differently, such as C# and Db, or F# and Gb. The choice depends on the musical context.
Accidental
A symbol that raises or lowers a note's pitch: sharp (#) raises by one semitone, flat (b) lowers by one semitone, and natural cancels a previous accidental.
Sharp
An accidental (#) that raises a note by one semitone. For example, F# is one semitone higher than F.
Flat
An accidental (b) that lowers a note by one semitone. For example, Bb is one semitone lower than B.
Natural
An accidental that cancels a sharp or flat, returning a note to its unaltered pitch. Also used to describe notes without any accidentals (e.g., the white keys on a piano).
🎸Chords15 terms
Chord
Three or more notes played simultaneously. Chords form the harmonic foundation of a song and are the building blocks of chord progressions.
Learn more →Triad
A three-note chord built by stacking two intervals of a third. The four basic triad types are major, minor, diminished, and augmented.
Learn more →Root
The note a chord is named after and built upon. In a C major chord (C-E-G), C is the root. The root establishes the chord's identity.
Learn more →Third
The note that determines whether a chord sounds major (happy) or minor (sad). A major third is 4 semitones above the root; a minor third is 3 semitones.
Learn more →Fifth
The stabilizing note in a chord, typically 7 semitones (a perfect fifth) above the root. A diminished fifth (6 semitones) creates tension; an augmented fifth (8 semitones) creates brightness.
Learn more →Seventh Chord
A four-note chord that adds a seventh interval above the root to a triad. Common types include major 7th (Cmaj7), dominant 7th (C7), and minor 7th (Cm7).
Learn more →Major Chord
A triad with a major third and perfect fifth above the root (e.g., C-E-G). Major chords generally sound bright, happy, and resolved.
Learn more →Minor Chord
A triad with a minor third and perfect fifth above the root (e.g., A-C-E). Minor chords generally sound darker, sadder, or more introspective than major chords.
Learn more →Diminished Chord
A triad with a minor third and diminished fifth above the root (e.g., B-D-F). Diminished chords sound tense and unstable, often used as passing chords.
Learn more →Augmented Chord
A triad with a major third and augmented fifth above the root (e.g., C-E-G#). Augmented chords sound bright and unresolved, creating a sense of upward motion.
Learn more →Suspended Chord (sus)
A chord where the third is replaced by a second (sus2) or fourth (sus4), creating an open, unresolved sound. For example, Csus4 is C-F-G instead of C-E-G.
Learn more →Power Chord
A two-note chord containing only the root and fifth (no third), commonly used in rock and metal. Power chords sound neither major nor minor.
Learn more →Slash Chord
A chord with a specific bass note written after a slash, like C/E (C major chord with E in the bass). Slash chords create smooth bass line movement between chords.
Learn more →Inversion
A chord rearrangement where a note other than the root is the lowest note. First inversion has the third in the bass; second inversion has the fifth in the bass.
Learn more →Voicing
The specific arrangement of a chord's notes across different octaves and instruments. The same chord can sound very different depending on its voicing.
🎹Scales & Modes10 terms
Scale
An ordered sequence of notes within an octave that defines the tonal material for a piece of music. Scales determine which notes sound "right" in a given key.
Learn more →Major Scale
The most common scale in Western music, following the pattern W-W-H-W-W-W-H (W = whole step, H = half step). The C major scale uses only white keys: C-D-E-F-G-A-B.
Learn more →Minor Scale
A family of scales that produce a darker sound than major. The three forms are natural minor (W-H-W-W-H-W-W), harmonic minor (raised 7th), and melodic minor (raised 6th and 7th ascending).
Learn more →Pentatonic Scale
A five-note scale widely used in rock, blues, pop, and folk music. The major pentatonic removes the 4th and 7th degrees; the minor pentatonic removes the 2nd and 6th.
Learn more →Blues Scale
A six-note scale based on the minor pentatonic with an added "blue note" (flat 5th). This extra note gives blues, rock, and jazz their characteristic gritty sound.
Learn more →Chromatic Scale
A twelve-note scale containing every semitone within an octave. It includes all possible notes in Western music and is used for chromatic runs and passing tones.
Learn more →Mode
A scale derived by starting on a different degree of a parent scale. The seven modes of the major scale each have a unique sound character, from bright (Lydian) to dark (Locrian).
Learn more →Ionian
The first mode of the major scale, identical to the major scale itself (W-W-H-W-W-W-H). It has a bright, happy, and resolved quality.
Learn more →Dorian
The second mode of the major scale, a minor scale with a raised 6th degree. Dorian has a jazzy, sophisticated minor sound and is popular in funk, jazz, and folk.
Learn more →Mixolydian
The fifth mode of the major scale, a major scale with a lowered 7th degree. Mixolydian has a bluesy, rock feel and is common in classic rock, country, and funk.
Learn more →🎶Harmony13 terms
Key
The tonal center of a piece of music, defined by a root note and a scale (e.g., "Key of C major"). The key determines which notes and chords sound natural together.
Learn more →Key Signature
The set of sharps or flats at the beginning of a staff that indicates the key of the music. For example, one sharp indicates G major or E minor.
Learn more →Diatonic
Notes or chords that belong to the current key and scale. Diatonic chords are the seven chords naturally built from a scale's notes, labeled with Roman numerals I through VII.
Learn more →Tonic
The "home base" note and chord (I) of a key. Music tends to feel resolved and at rest when it arrives at the tonic. In the key of C, the tonic chord is C major.
Learn more →Dominant
The fifth degree (V) of a scale and its chord. The dominant chord creates strong tension that naturally wants to resolve to the tonic (V to I), the most fundamental cadence in music.
Learn more →Subdominant
The fourth degree (IV) of a scale and its chord. The subdominant provides a sense of motion away from the tonic and often leads to the dominant or back to the tonic.
Learn more →Chord Progression
A sequence of chords played in order, forming the harmonic backbone of a song. Common progressions like I-V-vi-IV appear across countless pop and rock songs.
Learn more →Cadence
A chord pattern that creates a sense of resolution or pause, like musical punctuation. The most common is the authentic cadence (V to I), which feels like a strong ending.
Learn more →Resolution
The movement from a tense or unstable chord to a stable one, creating a sense of arrival. The classic resolution is from the dominant (V) chord to the tonic (I) chord.
Modulation
Changing from one key to another within a song. Modulation can create excitement (shifting up a half step) or provide contrast between song sections.
Borrowed Chord
A chord taken from the parallel key (e.g., using a chord from C minor while in C major). Borrowed chords add color and emotional depth, like the bVII or iv chord in a major key.
Secondary Dominant
A dominant chord (V) that temporarily points to a chord other than the tonic. For example, in C major, D7 acts as V/V, creating tension that resolves to G.
Substitute Chord
A chord used in place of another chord in a progression while maintaining a similar harmonic function. For example, Em can substitute for C because they share two notes (E and G).
🥁Rhythm3 terms
BPM (Beats Per Minute)
A measure of tempo indicating how many beats occur in one minute. A higher BPM means a faster tempo. Typical pop songs range from 100 to 130 BPM.
Time Signature
A notation that indicates how many beats are in each measure and which note value gets one beat. 4/4 (four quarter-note beats per measure) is the most common time signature.
Groove
A rhythmic pattern or feel that makes music move and feel alive. In OtoTheory, grooves are playback patterns (Straight, Bounce, Shuffle, etc.) that bring your chord progressions to life.
🎼Composition4 terms
Verse
A section of a song that typically carries the narrative or story, with lyrics that change each time it repeats. Verses usually share the same melody and chord progression.
Chorus
The main recurring section of a song that contains the central message or hook. The chorus usually has the same lyrics and melody each time and is the most memorable part.
Bridge
A contrasting section that appears once in a song, usually between the second chorus and final chorus. Bridges often introduce new chords, melodies, or lyrics to provide variety.
Capo
A clamp placed on the guitar neck to raise the pitch of all strings, allowing you to play in different keys using familiar chord shapes. OtoTheory supports capo positions in its fretboard display.
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