—v.koun"tur-stān'), [key] Histol.n.
a second stain of a different color applied to a microscopic specimen and used to color and contrast those parts not retaining the first stain.
to treat (a microscopic specimen) with a counterstain.
to become counterstained; take a counterstain.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.