heliometer

1 of 2

noun

: a visual telescope that has a divided objective designed for measuring the apparent diameter of the sun but also used for measuring angles between celestial bodies or between points on the moon

heliometric

2 of 2

adjective

: of, employing, or obtained by use of a heliometer
heliometric observations
heliometric results

Word History

Etymology

Noun

French héliomètre, from hélio- heli- entry 1 + -mètre -meter

Adjective

French héliométrique, from hélio- heli- entry 1 + -métrique -metric

First Known Use

Noun

1753, in the meaning defined above

Time Traveler
The first known use of heliometer was in 1753

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Cite this Entry

“Heliometer.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/heliometer. Accessed 7 Jul. 2026.

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