ratchet: [17] Ratchet was originally acquired, in the form rochet, from French rochet. This was a diminutive form descended ultimately from Frankish *rokko ‘spool’, which is related to English rocket. The notion of having teeth, which is central to the idea of a ratchet, therefore appears to be historically secondary; it presumably arose from the addition of ‘teeth’ to a rotating ‘spool’ or ‘spindle’ in a machine. The change from rochet to ratchet, which began in the 18th century, may have been influenced by German ratsch ‘ratchet’. => rocket
