back out vs crawfish

back out is not a noun while crawfish is a noun.

Word	Noun	Adjective	Verb	Adverb
back out	No	No	Yes	No
crawfish	Yes	No	Yes	No

As verbs, back out and crawfish are synonyms defined as:

back out and crawfish: make a retreat from an earlier commitment or activity

Other synonyms of back out include back away, crawfish out, pull back, pull in one's horns, retreat, withdraw.

back out (noun)	crawfish (noun)
	large edible marine crustacean having a spiny carapace but lacking the large pincers of true lobsters
	small freshwater decapod crustacean that resembles a lobster
	tiny lobster-like crustaceans usually boiled briefly

back out (verb)	crawfish (verb)
make a retreat from an earlier commitment or activity	make a retreat from an earlier commitment or activity
move out of a space backwards