Theory Glossary

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Guitar is life!
Guitar is life!


Theory Glossary

A list of musical theory terminology - the essential reference for theory students!

Note: Definitions of some terms were taken from Andrew's Theory Lessons. Please check his lessons to learn even more!


Accelerando: Gradually increasing in tempo.

Accented: A note is played more strongly and loudly than others. The symbol for an accent is a >.

Acciaccatura: A very fast grace note.

Accidental: A note that falls outside the key signature.

Anacrusis: A note or notes that come before the 1st beat of the 1st full bar.

Arpeggio: Notes from from a chord played one at a time.

Atonal: Music without any key. i.e. using all 12 notes. Chords are generally very dissonant.

Augmented Triad: Triad consisting of a root note, a major 3rd, an an Augmented 5th.


Bar: A regular collection of notes, each of the same duration in terms of the number of notes it contains. The duration of a bar in note terms is defined at the beginning by the time signature.

Bar Line: A vertical line which separates bars.

Binary Form: Music that just follows a two section AB form.

Broken Chord: A chord in which the notes are played one after another (not necessarily in order) instead of together.


Cadence: The chords at the end of a phrase.

CAGED System: A framework to hang your understanding of the different major scales and associated chords on. There are 2 main parts - first, a selection of scales, and second some associated chord shapes that work in the same position as the scales.

Canon: An instrumental round.

Chord: A number of notes played together at the same time.

Chord Change: Moving from one chord to another.

Chromatic: A scale using all twelve notes.

Circle of Fifths: An arrangement of musical keys in a circular format. Allows you to easily understand the relationship between keys, and work out the number of sharps and flats there are in each key.

Clef: Musical symbol used to indicate the pitch of the written notes, it is placed on one of the lines at the beginning of the staff.

Cluster: Chord consisting of notes very close together - very dissonant.

Consonance: Where the notes in a chord don't clash and sound "right" together.

Contrary Motion: Two parts move in opposite directions, one moves up while the other moves down.

Counter Melody: A melody that plays at the same time as the main melody, often harmonising it.

Crescendo: Gradually increasing in volume.


Diatonic Scale System: Refers to the types of scales almost exclusively used in western music. Consists of a mixture of half and whole tones.

Diminished Triad: Triad consisting of a root note, a minor 3rd, and a diminished 5th.

Diminuendo: Gradually decreasing in volume.

Dissonance: Where the notes in a chord clash and sound "wrong" together.

Dominant: Having a major fourth and a dominant seventh.

Dotted Note: A note with a small dot written after it. The dot adds a half as much again to the basic note's duration.

Dynamics: Different volumes in a piece of music.


Extended Chord: A chord which is extended further than a basic triad.


Flat: Lowers a note by one semi-tone. It is written as "b".

Form: The form of a piece of music is the way the different sections and ideas are put together.

Forte (f): played loudly

Fortissimo (ff): played very loudly


Glissando: A continuous sliding from one pitch to another.

Grace Note: An ornamental note which is played very fast just before another note.


Harmony: An enhancement of a melody line by playing notes at the same time either higher or lower than the melody note itself.

Hexatonic Scale: A scale with six notes per octave.

Homophony: One voice (or melody line) accompanied by chords.


Imperfect Cadence (I-V): Resolution involving a movement to the dominant is the second most most popular cadence, whether preceded by ii, IV, or I, or any other chord. It leaves the music unfinished and prepares the way for another section of music.

Interuppted Cadence (V-VI):

Movement from chord V to any chord except the I chord (typically vi, which is the relative minor key chord in major key). Again, an important cadence for giving music a thirst for continuation, it really makes the listener want to hear resolution.

Interval: The distance between two notes.

Inverted Pedal: A high note which is held or repeated while the chord changes underneath.



Key Signature: Shows the key that a piece is to be played in.It is written as a group of symbols at the beginning of the piece of music, listing either a number of sharps (#) or flats.


Ledger Line: Expresses notes that do not fall on the regular lines or spaces of the musical staff. A short line (slightly longer than the note) is drawn parallel to the lines on the staff (above or below as appropriate), corresponding to where the staff line would be if the note were in range.

Legato: Smooth, sustained, gently played music.


Major Scale: A scale of seven notes that goes T T S T T T S. In modes it is known as the Ionian mode.

Major Triad: Triad consisting of a root note, a 3rd, and a Perfect 5th.

Mezzo Forte (mf): played moderately loudly

Mezzo Piano (mp): played moderately quietly

Minor Scale: A scale of seven notes that goes T S T T S T T. In modes it is known as the Aeolian mode.

Minor Triad: Triad consisting of a root note, a minor 3rd, and a Perfect 5th.

Mode: A variaton of a scale used to create different effects within a song. The modes of the major scale are: Ionian, Dorian, Phrygian, Lydian, Mixolydian, Aeolian and Locrian. Each mode possesses a different formula. The Ionian mode is another name for the Major Scale and therefore posseses the same formula. The Aeolian mode is another name for the Minor Scale and it too, possesses the minor scale's formula.

Modulation: Changing from one key to another in the middle of a piece of music.


Note Value: Indicates the relative duration of a note.

Neopolitan Chord: A chord built off of the lowered second degree of a major or minor scale.


Octave: Interval between two notes with half or double its frequency. These two notes share the same name.

Ornament: A short, extra note added to a melody line to make it more interesting.

Ostinato: Short musical pattern that repeats itslef. Simlar to a riff.


Pause (Fermata): A note or chord is held on and the beat of the music stops temporarily.

Pedal: A bass note which is held or repeated. the chords and melody change over the top.

Pentatonic Scale: A scale with five notes per octave.

Perfect Cadence (V-I): Resolution consisting of the chords V - I. This cadence sounds "finished".

Piano (p): played quietly

Pianoissimo (pp): played very quietly

Pitch: The perceived fundamental frequency of a sound.

Plagal Cadence(IV-I): Resolution consisting of the chords IV - I. This cadence sounds "finished". It is less commonly used than the perfect cadence.

Polyphony: Several voices or melody lines accompanied by chords.

Powerchord: Two notes played together, a root note and a Perfect 5th interval, sometimes the root note's octave is added as well.


Quarter Tone: Half of a semi-tone. An pitch division not commonly used in western music.


Rallentando: Where the tempo gradually decreases.

Relative Minor: A scale that is "related" to a major scale.

Rest: An interval of silence in a piece of music, marked by a sign indicating the length of the pause. Each rest symbol corresponds with a particular note value.

Ritardando (similar to rallentando): Gradually decreasing in tempo. Opposite of accelerando.

Rondo Form: Music that follows an A-B-A-C-A-D-A form.

Root Note: The note(s) that define the sound of the scale. The scale is named after its root note.

Rubato: Flexible in tempo. Where the tempo is always sightly changing. Also known as free time.


Scale: A set of notes that have a particular sound or feeling to it.

Secondary Dominant: A Dominant 7th chord that isn't part of the key of the song, and is just being used to lead into the next chord. For example in: |C|Am|F-D7|G|, D7 is a secondary dominant, as it is the 5th of G.

Semitone: The smallest interval between two notes. e.g. C to C#

Sharp: Raises a note by one semi-tone. It is written as "#".

Slur: Symbol indicating that the notes it embraces are meant to be played without separation.

Staccato: Where notes are played very short and detached.

Staff: The series of vertical lines that music notation is based around. Staves are composed of five lines, these lines do not represent the strings on the guitar. --> Go to Music Notation Lesson <--


Tablature: Form of musical notation, which tells players where to place their fingers on a particular instrument rather than which pitches to play.

Tempo: The speed or pace of a given piece. Plural: tempi.

Ternary Form: Music that follow a three part ABA form.

Tierce de Picardie: In a minor key a perfect cadence that ends with a major chord.

Time Signature: Used in sheet music. Specifies how many beats are in each measure and one note value constitutes one beat.

Tonal: Music with a key. Chord are hardly ever dissonant.

Tone: Equal to two seimtones e.g. C to D

Transposition: Process of moving a collection of notes up or down in pitch by a constant interval.

Triad: The simplest form of a chord that contains at least 3 notes, root note, major third and perfect 5th. There are also other types of triads with different formulas.

Trill: A very fast alternation between 2 notes.



Vamp: Playing the root note of the chord followed by the other notes of the chord. Common technique in piano and ragtime bass lines.


Whole-Tone Scale:A scale that goes up in just whole tones. i.e. C Whole-Tone scale = C-D-E-F#-G#-A#