Acciaccatura - Musical Definition
Acciaccatura - Crushed in. A non-harmonic crushed note played as quickly as possible.
Musical examples where the term 'Acciaccatura' is used:
The ornament, which is crossed through with an oblique line, appears before the note it effects, usually accompanied by a slur. In theory the note is timeless and is crushed in as quickly as possible. There is no definitive rule about whether it falls on or before the beat, its use being governed by performance practice and even individual taste. Where it is played on the beat the rhythmic effect would be approximately as follows:
In this example, taken from the sixth movement of Mussorgsky’s Pictures at an Exhibition, the acciaccaturas are played before the beat:
Here also is a useful video explaining acciaccatura: