acciaccatura
n. countablen. a small note played very quickly before a main note. It is used in music to add a short, sharp sound to the main melody.
n. a grace note that is played simultaneously with the main note or immediately before it, typically in a rapid, percussive manner. Often used in Baroque and classical music to ornament a melody.
The pianist added an acciaccatura to the first note of the melody.
In the original score, the composer indicates an acciaccatura on the second beat to create a more dramatic entrance for the theme.
While the appoggiatura is held for a portion of the main note's duration, the acciaccatura is executed as a brief, detached strike that does not displace the primary rhythmic value.
Borrowed from Italian acciaccatura, from the verb acciaccare (“to crush”).