a cappella Vocal music, without instrumental accompaniment.
a tempo Return to the previous tempo.
accelerando Gradually speed up. (Abbreviated as accel.)
accent A note played louder or with more emphasis than regular notes.
accidental A marking used to raise and lower the indicated pitch. Sharps raise the note a half step, flats lower the note a half step, and naturals return the note to the original pitch.
adagietto Tempo marking for a moderately slow tempo, slightly faster than adagio.
adagio Tempo marking for a moderately slow tempo.
allegretto Tempo marking for a moderately fast tempo, not quite as fast as allegro.
allegro Tempo marking for a fast, cheerful tempo.
altered bass chord A chord with some note other than the ...