overestimate vs underestimate

overestimate and underestimate both are nouns.

Word	Noun	Adjective	Verb	Adverb
overestimate	Yes	No	Yes	No
underestimate	Yes	No	Yes	No

overestimate (noun)	underestimate (noun)
a calculation that results in an estimate that is too high	an estimation that is too low; an estimate that is less than the true or actual value
an appraisal that is too high

overestimate (verb)	underestimate (verb)
make too high an estimate of	make a deliberately low estimate
assign too high a value to	make too low an estimate of
	assign too low a value to