a person or thing that terminates.
Astronomy. the dividing line between the illuminated and the unilluminated part of a satellite or planet, especially the moon.

Origin of terminator

1760–70; < Late Latin terminātor, equivalent to terminā(re) to terminate + -tor -tor
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for terminator

Contemporary Examples of terminator

Historical Examples of terminator

  • The "terminator" is the boundary between the lighted and the dark portion of the disc.

  • The liberation of the tiny planet and consequent shifting of the terminator was bringing frigidity to Vulcan's Workshop.

    Vulcan's Workshop

    Harl Vincent

  • The general shape of this line is never a circle but always elliptical, and astronomers call it the terminator.


    David Todd

  • They would certainly be indicated on the terminator, and yet not a trace of such markings has been found.

    Mars and its Mystery

    Edward Sylvester Morse

  • If the Moon was as smooth as a billiard ball the terminator would be clear cut.

    Mars and its Mystery

    Edward Sylvester Morse

British Dictionary definitions for terminator



the line dividing the illuminated and dark part of the moon or a planet
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for terminator

1770, "line of separation between the bright and dark parts of a moon or planet," from Latin terminator, from terminare (see terminus). Meaning "one who terminates (something)" is attested from 1846.

Online Etymology Dictionary, © 2010 Douglas Harper