acciaccatura

n. (Music) brief embellishing note performed as fast as possible before a principal note

In music, ornaments are musical flourishes that are not necessary to the overall melodic (or harmonic) line, but serve to decorate or "ornament" that line. Many ornaments are performed as "fast notes" around a central note. The amount of ornamentation in a piece of music can vary from quite extensive (it was often so in the Baroque period) to relatively little or even none. The word agrément is used specifically to indicate the French Baroque style of ornamentation.
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Noun
1. an embellishing note usually written in smaller size
(synonym) grace note, appoggiatura
(hypernym) note, musical note, tone

n. bruise, contusion

(n.)
A short grace note, one semitone below the note to which it is prefixed; -- used especially in organ music. Now used as equivalent to the short appoggiatura.