n. [ Perh. fr. OF. saïn grease, fat + de of + verre glass (cf. Saim), or fr. F. sel de verre sandiver. ] A whitish substance which is cast up, as a scum, from the materials of glass in fusion, and, floating on the top, is skimmed off; -- called also glass gall. [ Formerly written also sandever. ] [ 1913 Webster ]