misprision (n.) Look up misprision at Dictionary.com
"wrong action, a failure on the part of authority," early 15c., from Anglo-French mesprisioun "mistake, error, wrong action or speech," from Old French mesprision "mistake, wrongdoing, fault, blame, crime," from mespris, past participle of mesprendre "to mistake, act wrongly, trespass, transgress, break a law," from mes- "wrongly" (see mis- (2)) + prendre "take," from Latin prendere, contracted from prehendere "seize" (see prehensile).

In 16c., misprision of treason was used for lesser degrees of guilt (those not subject to capital punishment), especially for knowing of treasonable actions or plots but not informing the authorities. This led to the common supposition in legal writers that the word means "failure to denounce" a crime.