Definition of D line
: a yellow persistent first line of the principal series of the sodium spectrum constituting in the Fraunhofer lines a doublet whose nearly equal components have wavelengths 5895.93 and 5889.96 angstroms respectively
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.
Join MWU now and get access to America’s largest dictionary, with:
- 300,000 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 D line? Please tell us where you read or heard it (including the quote, if possible).