overreckoning vs overestimation

overreckoning and overestimation both are nouns.

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

As nouns, overreckoning and overestimation are synonyms defined as:

overreckoning and overestimation: a calculation that results in an estimate that is too high

Other synonyms of overreckoning include overestimate, overrating.

overreckoning (noun)	overestimation (noun)
a calculation that results in an estimate that is too high	a calculation that results in an estimate that is too high
	an appraisal that is too high