O.E. fyllan, from P.Gmc. *fullijan (cf. O.S. fulljan, O.N. fylla, O.Fris. fella, Du. vullen, Ger. füllen "to fill"), a derivative of adj. *fullaz "full." The related noun meaning "a full supply" is M.E. fille, from O.E. fylle. To fill the bill (1882) was originally U.S. theatrical slang, in reference to a star whose name would be the only one on a show's poster. Related: Filled; filling.