cog vs join

cog and join both are nouns.

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

As verbs, join is a hypernym of cog; that is, join is a word with a broader meaning than cog:

cog (noun)	join (noun)
tooth on the rim of gear wheel	a set containing all and only the members of two or more given sets
a subordinate who performs an important but routine function	the shape or manner in which things come together and a connection is made

cog (verb)	join (verb)
join pieces of wood with cogs	make contact or come together
roll steel ingots	cause to become joined or linked
	become part of; become a member of a group or organization
	come into the company of
	be or become joined or united or linked