[as-id-fast, -fahst]

Origin of acid-fast

First recorded in 1900–05
Related formsac·id-fast·ness, noun Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for acid-fast

Historical Examples of acid-fast

British Dictionary definitions for acid-fast


  1. (of bacteria and tissues) resistant to decolorization by mineral acids after staining
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

acid-fast in Medicine


  1. Of or relating to bacteria that are not decolorized by an acidic alcohol solution after they have been stained.
Related formsacid-fast′ness n.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.