terminator

American  

[tur-muh-ney-ter] / ˈtɜr məˌneɪ tər /

noun

1. a person or thing that terminates.

2. Astronomy.  the dividing line between the illuminated and the unilluminated part of a satellite or planet, especially the moon.

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Etymology

Origin of terminator

1760–70; < Late Latin terminātor, equivalent to terminā ( re ) to terminate + -tor -tor

Example Sentences

Analyzing the planet's terminators, or the moving line separating the daylight and nocturnal sides of a given world, the scientists realized that there was tremendous asymmetry.

From Salon

One of the most disturbing observations for astronomers is the asymmetry between the planet's two terminators.

From Science Daily

The first thing to draw in is the terminator line.

From National Geographic Kids

As seen from the moon’s surface, anywhere along the terminator, the sun is rising and still low in the lunar sky.

From Scientific American

For example, the terminator at the start of Solar Cycle 24 happened later than expected, which allowed for less magnetic field growth during Solar Cycle 24, resulting in a weaker solar maximum.

From Scientific American