underestimate vs underreckoning

underestimate and underreckoning both are nouns.

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

As nouns, underestimate and underreckoning are synonyms defined as:

underestimate and underreckoning: an estimation that is too low; an estimate that is less than the true or actual value

Other synonyms of underestimate include underestimation, underrating.

underestimate (noun)	underreckoning (noun)
an estimation that is too low; an estimate that is less than the true or actual value	an estimation that is too low; an estimate that is less than the true or actual value

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