You must — there are over 200,000 words in our free online dictionary, but you are looking for one that’s only in the Merriam-Webster Unabridged Dictionary.
Start your free trial today and get unlimited access to America's largest dictionary, with:
New Latin, from peri- + Greek astron star
Keep scrolling for more
Cite this Entry
“Periastron.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/periastron. Accessed 25 Feb. 2021.
Comments on periastron
What made you want to look up periastron? Please tell us where you read or heard it (including the quote, if possible).
See Definitions and Examples »
Get Word of the Day daily email!
More Confusing Words—Quiz
Can you spell these 10 commonly misspelled words?
Spell words. Make bears.
Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!
From ideals to friendships
Words from the week of 2/19/2021
Rest on them, but not for too long
And 'mood board' too
We're intent on clearing it up
We're gonna stop you right there
How to use a word that (literally) drives some pe...
The awkward case of 'his or her'
How many of these commonly confused words do you ...
A quiz for lovers and haters