termĭnātor, ōris, m. [termino],
he who limits , sets bounds , Aug. Civ. Dei, 4, 11.
·noun One who, or that which, terminates. II. Terminator ·noun The dividing line between the illumi...
Webster's Dictionary of the English Language
The line separating the illuminated from the dark portion of the moon's disc. ...
The Sailor's Word-Book