- A pawl, click, or detent, for holding or propelling a
ratchet wheel, or ratch, etc. - A mechanism composed of a ratchet wheel, or ratch, and
pawl. See Ratchet wheel, below, and 2d Ratch.
Meaning of 'ratchet' (Princeton's WordNet)
1 . ratchet
[ v]
Meaning (1): - move by degrees in one direction only