In sound, the first instant of a note's arrival; in threat, the move against — context decides, and this house builds for the first sense.
Old Italian attaccare (to attach, to join in battle), from a- (to) + taccare (to fasten), of Frankish origin; in sound, the first instant of a note's arrival, a striking-in.
In sound, the first instant of a note's arrival, the sense this house builds for.