Misprision

n.
  1. The act of misprising; misapprehension; misconception; mistake.
  2. Neglect; undervaluing; contempt.
  3. (Law) A neglect, negligence, or contempt.

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: -- 1. Misprision of treason, which is omission to notify the authorities of an act of treason by a person cognizant thereof. Stephen. 2. Misprision of felony, which is a concealment of a felony by a person cognizant thereof. Stephen.