ratch·et
noun/ˈrætʃɪt/
/ˈrætʃɪt/
- a wheel or bar with teeth along the edge and a metal piece that fits between the teeth, allowing movement in one direction only
enlarge image（防止倒转的）棘轮，棘齿 Word Originmid 17th cent.: from French rochet, originally denoting a blunt lance head, later in the sense ‘bobbin, ratchet’; related to the base of archaic rock ‘quantity of wool on a distaff for spinning’.