ac·com·plice /ə-'käm-pləs, -'kəm-/ n [alteration (from incorrect division of a complice ) of complice, from Middle French, associate, from Late Latin complic - complex partner, confederate]: one who intentionally and voluntarily participates with another in a crime by encouraging or assisting in the commission of the crime or by failing to prevent it though under a duty to do so
the accomplice of the burglar
an accomplice in a robbery
Merriam-Webster’s Dictionary of Law. Merriam-Webster. 1996.