noun. An embellishing note, usually one step above or below the note it precedes and indicated by a small note or special sign.

noun. In music, a small additional note of embellishment, preceding the note with which it is connected, and taking away from that note a portion of its time.

noun. A passing tone preceding an essential tone, and borrowing the time it occupies from that; a short auxiliary or grace note one degree above or below the principal note unless it be of the same harmony; -- generally indicated by a note of smaller size, as in the illustration above. It forms no essential part of the harmony.

noun. A type of musical ornament, falling on the beat, which often creates a suspension and subtracts for itself half the time value of the principal note which follows.

noun. an embellishing note usually written in smaller size

"The appoggiatura was formerly classified into _long appoggiatura_ and _short appoggiatura_, but modern writers seem to consider the term "short appoggiatura" to be synonymous with acciaccatura [12], and to avoid confusion the word _acciaccatura_ will be used in this sense, and defined under its own heading."

musical note  note  tone  

appoggiature