abet /ə-'bet/ vt abet·ted, abet·ting: to assist, encourage, instigate, or support with criminal intent in attempting or carrying out a crime
— often used in the phrase aid and abet
abet·ment n
abet·tor also abet·ter /ə-'be-tər/ n
Merriam-Webster’s Dictionary of Law. Merriam-Webster. 1996.