a deviation from accuracy or correctness; a mistake, as in action or speech

His speech contained several factual errors.

belief in something untrue; the holding of mistaken opinions.

the condition of believing what is not true

in error about the date.

a moral offense; wrongdoing; sin.

Baseball . a misplay that enables a base runner to reach base safely or advance a base, or a batter to have a turn at bat prolonged, as the dropping of a ball batted in the air, the fumbling of a batted or thrown ball, or the throwing of a wild ball, but not including a passed ball or wild pitch.

Mathematics . the difference between the observed or approximately determined value and the true value of a quantity.

Law .

a mistake in a matter of fact or law in a case tried in a court of record.

writ of error.

Philately . a stamp distinguished by an error or errors in design, engraving, selection of inks, or setting up of the printing apparatus. Compare freak 1 ( def. 5 ) , variety ( def. 8 ) .

adjective

correct , exact , precise , right , rigorous