cog vs tooth

cog and tooth both are nouns.

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

As nouns, tooth is a hypernym of cog; that is, tooth is a word with a broader meaning than cog:

cog (noun)	tooth (noun)
tooth on the rim of gear wheel	a means of enforcement
a subordinate who performs an important but routine function	toothlike structure in invertebrates found in the mouth or alimentary canal or on a shell
	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

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