A percussive version of a grace note, played quickly (and usually lightly) before the primary note. The flam and numerous combinations with additional notes are included in the 26 basic drum rudiments, a collection of patterns established by the National Association of Rudimental Drummers.
In the world of MIDI sequencing the term flam has been applied to two near-simultaneous notes of the same pitch, which sometimes arise from an error in copying and pasting. The near-duplicate notes often create playback glitches such as abruptly cutting off the sound or “squashing” an attack.