transitive verb Date: 1895 to stain (as a microscopy specimen) so as to color parts (as the cytoplasm of cells) not colored by another stain (as a nuclear stain), ~ noun
COUNTERSTAIN
Meaning of COUNTERSTAIN in English
Merriam Webster. Explanatory English dictionary Merriam Webster. Толковый словарь английского языка Мерриам-Уэбстер. 2012