tormentor

Strong’s Dictionary of Greek Words:

Greek:
βασανιστής
Transliteration:
basanistes
Phonic:
bas-an-is-tace’
Meaning:
from 928; a torturer
KJV Usage:
tormentor

From Manners and Customs of the Bible:

Matthew 18:3434And his lord was wroth, and delivered him to the tormentors, till he should pay all that was due unto him. (Matthew 18:34). His lord was wroth, and delivered him to the tormentors, till he should pay all that was due unto him.
The “tormentors” are the jailers, who were allowed to scourge and torture the poor debtors in their care in order to get money from them for the grasping creditors, or else to excite the compassion of friends, and obtain the amount of the debt from them. “In early times of Rome there were certain legal tortures, in the shape, at least, of a chain weighing fifteen pounds, and a pittance of food barely sufficient to sustain life, (see Arnold's History of Rome, vol.1, p. 136,) which the creditor was allowed to apply to the debtor for the purpose of bringing him to terms; and no doubt they often did not stop here” (Trench, Notes on the Parables, Am. Ed., p. 133).