he·​li·​om·​e·​ter ˌhē-lē-ˈä-mə-tər How to pronounce heliometer (audio)
: 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 adjective
heliometrically adverb

Word History


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

First Known Use

1753, in the meaning defined above

Time Traveler
The first known use of heliometer was in 1753

Dictionary Entries Near heliometer

Cite this Entry

“Heliometer.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/heliometer. Accessed 1 Feb. 2023.

More from Merriam-Webster on heliometer

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

The Great British Vocabulary Quiz

  • union jack speech bubble
  • Named after Sir Robert Peel, what are British police called?
Name That Thing

You know what it looks like… but what is it called?

Solve today's spelling word game by finding as many words as you can with using just 7 letters. Longer words score more points.

Can you make 12 words with 7 letters?