What does accomplice mean?
The definition of accomplice
Ac*com”plice, n.
Etym: [Ac- (perh. for the article a or for L. ad) + E. complice. See Complice.]

1 A cooperator. [R.] Success unto our valiant general, And happiness to his accomplices! Shak.
2 (Law)
An associate in the commission of a crime; a participator in an offense, whether a principal or an accessory. “And thou, the cursed accomplice of his treason.” Johnson.

Note: It is followed by with or of before a person and by in (or sometimes of) before the crime; as, A was an accomplice with B in the murder of C. Dryden uses it with to before a thing. “Suspected for accomplice to the fire.” Dryden.
Synonyms
— Abettor; accessory; assistant; associate; confederate; coadjutor; ally; promoter. See Abettor.