tooth vs cog

tooth and cog both are nouns.

Word	Noun	Adjective	Verb	Adverb
tooth	Yes	No	No	No
cog	Yes	No	Yes	No

As nouns, cog is a hyponym of tooth; that is, cog is a word with a more specific, narrower meaning than tooth:

Other hyponyms of tooth include sprocket.

tooth (noun)	cog (noun)
a means of enforcement	tooth on the rim of gear wheel
toothlike structure in invertebrates found in the mouth or alimentary canal or on a shell	a subordinate who performs an important but routine function
something resembling the tooth of an animal
one of a number of uniform projections on a gear
hard bonelike structures in the jaws of vertebrates; used for biting and chewing or for attack and defense

tooth (verb)	cog (verb)
	join pieces of wood with cogs
	roll steel ingots