Yours, Etc.: Origins and Uses of 8 Sign-Offs
formal notice to a plaintiff that the prosecutor will not continue a suit, Latin, literally "to be unwilling to pursue." The verb nolle-pross is attested from 1880.
in Anglo-American law, request by a prosecutor in a criminal action that the prosecution of the case cease, either on some or all of the counts or with respect to some or all of the defendants. It usually is used when there is insufficient evidence to ensure successful prosecution or when there has been a settlement between the parties out of court. The term also has been applied to the cessation of a civil suit