Continuing this short series of musical terms (and the list is by no means exhaustive!).
Idée Fixe - A recurring theme or figure associated with a person or action.
Imitation - Where one part copies another, often in fugue.
Imperfect Cadence - Two chords that finish with the dominant.
Improvisation - Made up on the spot.
Incidental Music - Music for a play, often dances, songs or even an overture.
Interlude - A short piece of music interspersed between other sections of a larger work.
Intermezzo - A short piano piece or an instrumental piece played by the orchestra in an opera with no action on stage.
Interrupted Cadence - A cadence that goes from the dominant to any other chord except the tonic.
Interval - The distance between two notes.
Inversion - A chord that is played in a position different to root position.
Jig - Fast dance from Ireland. Usually in compound time.
K-Pop - South Korean pop music.
Key Signature - Sharps or flats that appear at the beginning of a piece of music. It is repeated on every single line of music.
Larghetto - Broad and slow, but not as much as Largo.
Largo - Slow and broad tempo.
Leading Note - Seventh note of a scale.
Ledger Lines - Extra lines used above and below the stave to write higher and lower notes.
Legato - Play smoothly.
Leitmotiv - A recurring theme associated with a particular character or object. Used in opera a lot, but also in film music.
Lento - Slow tempo.
Libretto - The text of an opera, oratorio or musical.
Lied - German song.