What's Trending Now
More Trending Words
M star
noun
Definition of M star
: a red star characterized primarily by a surface temperature of 3,000 kelvins or less —called also Type M star
Explore M-W
There's more!
Love words? 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:
- More than 250,000 words that aren't in our free dictionary
- Expanded definitions, etymologies, and usage notes
- Advanced search features
- Ad free!
First Known Use of m star
1927
Seen and Heard
What made you want to look up M star? Please tell us where you read or heard it (including the quote, if possible).
Writing? Check your grammar now!