"wheel having teeth or cogs," early 15c., from cog (n.) + wheel (n.).
Entries linking to cog-wheel
cog n.
c. 1300, "wheel having teeth or cogs;" late 14c., "tooth on a wheel," probably a borrowing from a Scandinavian language (compare Norwegian kugg "cog") and cognate with Middle High German kugel "ball."
wheel n.
Old English hweol, hweogol "wheel," from Proto-Germanic *hwewlaz (source also of Old Norse hvel, Old Swedish hiughl, Old Frisian hwel, Middle Dutch weel), from PIE *kw(e)-kwl-o- "wheel, circle," suffixed, reduplicated form of root *kwel- (1) "revolve, move round; sojourn, dwell."
Figurative sense is early 14c. Wheel of fortune attested from early 15c. Slang wheels "a car" is recorded from 1959. Wheeler-dealer is from 1954, a rhyming elaboration of dealer.