terminator

noun

ter·​mi·​na·​tor ˈtər-mə-ˌnā-tər 

1

: the dividing line between the illuminated and the unilluminated part of the moon's or a planet's disk

2

: one that terminates

Examples of terminator in a Sentence

Recent Examples on the Web

Look 10 degrees below the lunar equator to find a string of three enormous impact sites resting on the terminator. —Anthony Wood, Space.com, 24 Feb. 2026

This is prime time for lunar viewing, with shadows from mountains and craters stretched dramatically close to the terminator — the line between lunar night and day. —Jamie Carter, Forbes.com, 19 Jan. 2026

While the terminator model has caught on, plenty of other ways of thinking about the sun exist—some of them with more physics reasoning underlying them. —Sarah Scoles, Scientific American, 10 Dec. 2025

On Mercury, the dividing line between day and night, the terminator, is more than just a twilight zone. —Kaif Shaikh, Interesting Engineering, 13 Nov. 2025

Word History

First Known Use

1652, in the meaning defined at sense 2

Rhymes for terminator

• activator
• actuator
• agitator
• alligator
• allocator
• alternator
• animator
• annotator
• applicator
• arbitrator
• aspirator
• aviator