Detent

De‐tent″ (?), n. [F. détente, fr. détendre to unbend, relax; pref. dé- (L. dis- or de) + tendre to stretch. See Distend.] (Mech.) That which locks or unlocks a movement; a catch, pawl, or dog; especially, in clockwork, the catch which locks and unlocks the wheelwork in striking.