detent

 
Pronunciation: /dɪˈtɛnt/

noun

  • a catch in a machine which prevents motion until released: a system of detents is used to ensure that gears are held in whatever position is selected [as modifier]: a detent spring
  • a catch that regulates striking in a clock.

Origin:

late 17th century (denoting a catch in a clock): from French détente, from Old French destente, from destendre 'slacken', from des- (expressing reversal) + Latin tendere 'to stretch'