detent

English Thesaurus

1. a hinged catch that fits into a notch of a ratchet to move a wheel forward or prevent it from moving backward (noun.artifact)

hypernym	:	catch, stop,
definition	:	a restraint that checks the motion of something (noun.artifact)

part meronym	:	rachet, ratch, ratchet,
definition	:	mechanical device consisting of a toothed wheel or rack engaged with a pawl that permits it to move in only one direction (noun.artifact)