n. 1. (Zool.) (a) The European redstart; -- so called from its white forehead. (b) The whitethroat; -- so called from its gray head. (c) The European tree sparrow. [ 1913 Webster ] 2. A wave whose crest breaks into white foam, as when the wind is freshening. [ 1913 Webster ] 3. A member of a self-appointed vigilance committee attempting by lynch-law methods to drive away or coerce persons obnoxious to it. Some early ones wore white hoods or masks. [ U. S. ] -- White"cap`, v. -- White"cap`per n. [ Webster 1913 Suppl. ] | 