Emily Dickinson Lexicon

AC-COM'PLICE, n. [Fr. complice; L. complicatus, folded together, of con, with, and plico, to fold; W. plegy, to plait; Arm. plega. See Complex and Pledge.]

An associate in a crime; a partner or partaker in guilt. It was formerly used in a good sense for a co-operator, but this sense is wholly obsolete. It is followed by with before a person; as, A was an accomplice with B in the murder of C. Dryden uses it with to before a thing.