overestimation vs estimate

overestimation and estimate both are nouns.

Word	Noun	Adjective	Verb	Adverb
overestimation	Yes	No	No	No
estimate	Yes	No	Yes	No

As nouns, estimate is a hypernym of overestimation; that is, estimate is a word with a broader meaning than overestimation:

Other hypernyms of overestimation include approximation, estimation, idea.

As nouns, estimate is a hypernym of overestimation; that is, estimate is a word with a broader meaning than overestimation:

overestimation: an appraisal that is too high
estimate: a document appraising the value of something (as for insurance or taxation)

Other hypernyms of overestimation include appraisal, estimation.

overestimation (noun)	estimate (noun)
a calculation that results in an estimate that is too high	a judgment of the qualities of something or somebody
an appraisal that is too high	an approximate calculation of quantity or degree or worth
	the respect with which a person is held
	a document appraising the value of something (as for insurance or taxation)
	a statement indicating the likely cost of some job

overestimation (verb)	estimate (verb)
	judge tentatively or form an estimate of (quantities or time)
	judge to be probable