stand firm vs fight down

stand firm and fight down both are verbs.

Word	Noun	Adjective	Verb	Adverb
stand firm	No	No	Yes	No
fight down	No	No	Yes	No

As verbs, fight down is a hypernym of stand firm; that is, fight down is a word with a broader meaning than stand firm:

Other hypernyms of stand firm include defend, fight, fight back, oppose.

stand firm (verb)	fight down (verb)
refuse to abandon one's opinion or belief	fight against or resist strongly
stand up or offer resistance to somebody or something