travail vs overkill

travail and overkill both are nouns.

Word	Noun	Adjective	Verb	Adverb
travail	Yes	No	Yes	No
overkill	Yes	No	No	No

As nouns, overkill is a hyponym of travail; that is, overkill is a word with a more specific, narrower meaning than travail:

travail: use of physical or mental energy; hard work
overkill: any effort that seems to go farther than would be necessary to achieve its goal

travail (noun)	overkill (noun)
use of physical or mental energy; hard work	any effort that seems to go farther than would be necessary to achieve its goal
concluding state of pregnancy; from the onset of contractions to the birth of a child	the capability to obliterate a target with more weapons (especially nuclear weapons) than are required

travail (verb)	overkill (verb)
work hard