hunker down vs sit down

hunker down and sit down both are verbs.

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

As verbs, sit down is a hypernym of hunker down; that is, sit down is a word with a broader meaning than hunker down:

hunker down: sit on one's heels
sit down: be in a position in which one's upper body is largely upright and supported by one's backside

Other hypernyms of hunker down include sit.

hunker down (verb)	sit down (verb)
hold stubbornly to a position	show to a seat; assign a seat for
sit on one's heels	be in a position in which one's upper body is largely upright and supported by one's backside
take shelter	take a seat