coun·​ter·​stain ˈkau̇n-tər-ˌstān How to pronounce counterstain (audio)
counterstained; counterstaining; counterstains

transitive verb

: to stain (something, such as a microscopy specimen) so as to color parts (such as the cytoplasm of cells) not colored by another stain (such as a nuclear stain)
counterstain noun

Word History

First Known Use

1895, in the meaning defined above

Time Traveler
The first known use of counterstain was in 1895

Dictionary Entries Near counterstain

Cite this Entry

“Counterstain.” Dictionary, Merriam-Webster, Accessed 29 Nov. 2023.

Medical Definition


1 of 2 noun
coun·​ter·​stain -ˌstān How to pronounce counterstain (audio)
: a stain used to color parts of a microscopy specimen not affected by another stain
especially : a cytoplasmic stain used to contrast with or enhance a nuclear stain


2 of 2 transitive verb
: to stain (a tissue or microscopy specimen) with an additional usually contrasting color
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