From a derivative of mainomai (meaning a prophet, as supposed to rave through inspiration); to divine, i.e. Utter spells (under pretense of foretelling -- by soothsaying.
KJV: And it came to pass, as we went to prayer, a certain damsel possessed with a spirit of divination met us, which brought her masters much gain by soothsaying:
NASB: It happened that as we were going to the place of prayer, a slave-girl having a spirit of divination met us, who was bringing her masters much profit by fortune-telling.