principal line

noun

Definition of principal line 

: the first and most intense line of a spectral line series

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!

Learn More about principal line

Share principal line

Statistics for principal line

Look-up Popularity

Comments on principal line

What made you want to look up principal line? Please tell us where you read or heard it (including the quote, if possible).

WORD OF THE DAY

a magnificent or impressive array

Get Word of the Day daily email!

Test Your Vocabulary

Name that Food Quiz

Name That Thing

Test your visual vocabulary with our 10-question challenge!

TAKE THE QUIZ
SCRABBLE® Sprint

Test Your Knowledge - and learn some interesting things along the way.

TAKE THE QUIZ

Love words? Need even more definitions?

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