RABBLE (ἀγοραι̂ος, G61). An unruly, lawless group of men who are ready to join a mob (Acts 17:5; KJV BASER SORT).

International Standard Bible Encyclopedia (1915)

rab’-l: This word is not found in the King James Version. the Revised Version (British and American) has it once as the translation of agoraios (literally, "lounger in the market place"), in Ac 17:5, where it replaces "baser sort" of the King James Version. It has the common meaning of an unruly, lawless set who are ready to join a mob.