Definition of cosmic year
: the estimated time required for a star at the sun's distance from the center of the Milky Way galaxy to make one trip around it in a circular orbit, about 200 million years
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!
Seen and Heard
What made you want to look up cosmic year? Please tell us where you read or heard it (including the quote, if possible).