sustain vs vouch

sustain and vouch both are verbs.

Word	Noun	Adjective	Verb	Adverb
sustain	No	No	Yes	No
vouch	No	No	Yes	No

As verbs, vouch is a hyponym of sustain; that is, vouch is a word with a more specific, narrower meaning than sustain:

Other hyponyms of sustain include back, back up, verify, demonstrate, establish, prove, shew, show, document, validate.

sustain (verb)	vouch (verb)
undergo (as of injuries and illnesses)	give supporting evidence
establish or strengthen as with new evidence or facts	summon (a vouchee) into court to warrant or defend a title
admit as valid	give personal assurance; guarantee
supply with necessities and support	give surety or assume responsibility
provide with nourishment
be the physical support of; carry the weight of
lengthen or extend in duration or space