“fast blue”

We have one entry that includes the term fast blue.

wool fast blue

noun, often capitalized W&F&B

: any of several blue azine acid dyes

See the full definition

Word of the Day

Listen to the pronunciation of career

See Definitions and Examples »

Test Your Vocabulary

Fashionable Words

  • dog-sunglasses-scarf
  • Which of these items is named for a deadly weapon?
True or False

Test your knowledge - and maybe learn something along the way.

TAKE THE QUIZ
Play Blossom: Solve today's spelling word game by finding as many words as you can using just 7 letters. Longer words score more points.

Pick the best words!

PLAY
Love words? Need even more definitions?

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

Games & Quizzes

See All
Play Quordle: Guess all four words in a limited number of tries. Each of your guesses must be a real 5-letter word.
Quordle Can you solve 4 words at once?
Play Blossom: Solve today's spelling word game by finding as many words as you can using just 7 letters. Longer words score more points.
Blossom Word Game Pick the best words!
Play Missing Letter: a crossword with a twist. Each of the 25 puzzle words start with a different letter of the alphabet. Which letter is missing?
Missing Letter A daily crossword with a twist
clapperboard-popcorn
Hollywood Lingo Quiz Are you a showbiz whiz?
See All