n. 1.the opposition or dissimilarity of things that are compared 2.the act of distinguishing by comparing differences 3.a conceptual separation or demarcation 4.the perceptual effect of the juxtaposition of very different colors 5.the range of optical density and tone on a photographic negative or print (or the extent to which adjacent areas on a television screen differ in brightness) contrast v. 1.put in opposition to show or emphasize differences 2.to show differences when compared