epistasis

noun, plural e·pis·ta·ses [ih-pis-tuh-seez] /ɪˈpɪs təˌsiz/.

Genetics. a form of interaction between nonallelic genes in which one combination of such genes has a dominant effect over other combinations.
Medicine/Medical.
1. the stoppage of a secretion or discharge.
2. a scum that forms on a urine specimen upon standing.

noun

obsolete scum on the surface of a liquid, esp on an old specimen of urine
med the arrest or checking of a bodily discharge, esp bleeding
Also called: hypostasis genetics the suppression by a gene of the effect of another gene that is not its allele

medical Latin, from Greek epistasis “a stopping, stoppage,” from epi “upon” (see epi-) + stasis “a stopping or standing” (see stasis).

n. pl. e•pis•ta•ses (-sēz′)

A film that forms over the surface of a urine specimen.
An interaction between nonallelic genes, especially an interaction in which one gene suppresses the expression of another.
The suppression of a bodily discharge or secretion.