hunker down vs crouch

hunker down is not a noun while crouch is a noun.

Word	Noun	Adjective	Verb	Adverb
hunker down	No	No	Yes	No
crouch	Yes	No	Yes	No

As verbs, hunker down and crouch are synonyms defined as:

Other synonyms of hunker down include hunker, scrunch, scrunch up, squat.

hunker down (noun)	crouch (noun)
	the act of bending low with the limbs close to the body

hunker down (verb)	crouch (verb)
hold stubbornly to a position	sit on one's heels
sit on one's heels	bend one's back forward from the waist on down
take shelter