[n. koun-ter-steyn; v. koun-ter-steyn] 
Histology| 1. | 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. |
| 2. | to treat (a microscopic specimen) with a counterstain. |
| 3. | to become counterstained; take a counterstain. |
counterstain coun·ter·stain (koun'tər-stān')
n.
A stain of a contrasting color used to color the components in a microscopic specimen that are not made visible by the principal stain.
tərˌsteɪn