orrho-(bef. a vowel orrh-), comb. form of Gr. ὀρρό-ς serum, in a few rarely used terms of pathology, etc., as ˈorrhocyst, -ˈcystis, a serous cyst; orrhymeˈnitis, inflammation of a serous membrane; also, ˈorrhoida., of the appearance or nature of serum (Mayne Expos.Lex. 1857); ˈorrhousa., serous (Syd. Soc.Lex. 1892).