succumb vs buckle under

succumb and buckle under both are verbs.

Word	Noun	Adjective	Verb	Adverb
succumb	No	No	Yes	No
buckle under	No	No	Yes	No

As verbs, succumb and buckle under are synonyms defined as:

Other synonyms of succumb include give in, knuckle under, yield.

succumb (verb)	buckle under (verb)
consent reluctantly	consent reluctantly
be fatally overwhelmed