semimajor axis

noun

semi·​ma·​jor axis ˌse-mē-ˈmā-jər- How to pronounce semimajor axis (audio)
ˌse-ˌmī-,
-mi-
: one half of the major axis of an ellipse (such as that formed by the orbit of a planet)

Example Sentences

Recent Examples on the Web The uncertainty in its semimajor axis (the radius of its orbit at its two most separated points) is just six meters out of a total length of 168,505,699.049 kilometers. Dante S. Lauretta, Scientific American, 1 Aug. 2016

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'semimajor axis.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Word History

First Known Use

1818, in the meaning defined above

Time Traveler
The first known use of semimajor axis was in 1818

Dictionary Entries Near semimajor axis

Cite this Entry

“Semimajor axis.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/semimajor%20axis. Accessed 26 Mar. 2023.

More from Merriam-Webster on semimajor axis

Last Updated: - Updated example sentences
Love words? Need even more definitions?

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


Challenging Standardized Test Words, Vol. 2

  • a pencil broken in half on top of a test answer sheet
  • The business’s new computer system proved not to be a panacea.
How Strong Is Your Vocabulary?

Test your vocabulary with our 10-question quiz!

TAKE THE QUIZ
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?

PLAY