consider vs rethink

consider is not a noun while rethink is a noun.

Word	Noun	Adjective	Verb	Adverb
consider	No	No	Yes	No
rethink	Yes	No	Yes	No

As verbs, rethink is a hyponym of consider; that is, rethink is a word with a more specific, narrower meaning than consider:

consider (noun)	rethink (noun)
	thinking again about a choice previously made

consider (verb)	rethink (verb)
deem to be	change one's mind
take into consideration for exemplifying purposes
regard or treat with consideration, respect, and esteem
judge or regard; look upon; judge
show consideration for; take into account
think about carefully; weigh
give careful consideration to
look at attentively
look at carefully; study mentally