The Collaborative International Dictionary
Misprision \Mis*pri"sion\, n. [LL. misprisio, or OF. mesprison, prop., a mistaking, but confused with OF. mespris contempt, F. m['e]pris. See 2d Misprise, Misprize, Prison.]
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The act of misprising; misapprehension; misconception; mistake. [Archaic]
--Fuller.The misprision of this passage has aided in fostering the delusive notion.
--Hare. Neglect; undervaluing; contempt. [Obs.]
--Shak.-
(Law) A neglect, negligence, or contempt. Note: In its larger and older sense it was used to signify ``every considerable misdemeanor which has not a certain name given to it in the law.'' --Russell. In a more modern sense it is applied exclusively to two offenses:
Misprision of treason, which is omission to notify the authorities of an act of treason by a person cognizant thereof.
--Stephen.Misprision of felony, which is a concealment of a felony by a person cognizant thereof.
--Stephen.
Wikipedia
Misprision of treason is an offence found in many common law jurisdictions around the world, having been inherited from English law. It is committed by someone who knows a treason is being or is about to be committed but does not report it to a proper authority.
Usage examples of "misprision of treason".
Parliament was summoned in December, and just before it convened on the sixteenth of January, many of the Duke of Norfolk's relatives were found guilty of misprision of treason for concealing Catherine's lack of chastity.