acid-fast

adjective
ac·​id-fast | \ ˈa-səd-ˌfast How to pronounce acid-fast (audio) \

Definition of acid-fast

: not easily decolorized by acids

First Known Use of acid-fast

1903, in the meaning defined above

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Time Traveler for acid-fast

Time Traveler

The first known use of acid-fast was in 1903

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Dictionary Entries Near acid-fast

acid egg

acid-fast

acid fog

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Cite this Entry

“Acid-fast.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/acid-fast. Accessed 21 Jan. 2022.

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More Definitions for acid-fast

acid-fast

adjective
\ ˈas-əd-ˌfast How to pronounce acid-fast (audio) \

Medical Definition of acid-fast

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

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