acid-fast

[ as-id-fast, -fahst ]

adjective

1. resistant to decolorizing by acidified alcohol after staining.

acid-fast

adjective

1. (of bacteria and tissues) resistant to decolorization by mineral acids after staining

Other Words From

• acid-fastness noun

Word History and Origins

Origin of acid-fast¹

First recorded in 1900–05

Example Sentences

It is a powerful oxidising agent and rapidly destroys most bacteria, but tubercle and other acid-fast organisms resist its lethal action for considerable periods, and upon this fact the method is based.

From Project Gutenberg

It belongs to that small group known as acid-fast bacteria.

From Project Gutenberg

This method is supposed to differentiate between B. tuberculosis and other acid-fast micro-organisms.

From Project Gutenberg