acid-fast

adjective
ac·​id-fast | \ˈa-səd-ˌfast \

Definition of acid-fast 

: not easily decolorized by acids

First Known Use of acid-fast

1903, in the meaning defined above

Keep scrolling for more

Learn More about acid-fast

Statistics for acid-fast

Look-up Popularity

Time Traveler for acid-fast

The first known use of acid-fast was in 1903

See more words from the same year

Keep scrolling for more

More Definitions for acid-fast

acid-fast

adjective
\ˈas-əd-ˌfast \

Medical Definition of acid-fast 

: not easily decolorized by acids (as when stained) used especially of bacteria and tissues

More from Merriam-Webster on acid-fast

See words that rhyme with acid-fast

Comments on acid-fast

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

WORD OF THE DAY

to clear from alleged fault or guilt

Get Word of the Day daily email!

Test Your Vocabulary

Difficult Vocab Quiz

  • the-education-of-achilles-eugne-delacroix
  • Which is a synonym of discomfit?
Spell It

Can you spell these 10 commonly misspelled words?

TAKE THE QUIZ
Word Winder's CrossWinder

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!