汗牛充栋 hànniúchōngdòng immense collection of books Origin Definitions Defs Strokes Stroke Words Sentences Sents 汗 hàn noun sweat sweat; perspiration; to sweat牛 niú noun ox ox; cow; bull; cattle; any of various bovine animals充 chōng verb to fill (bound form) to fill; to pack; to charge a battery栋 棟 dòng house (literary) a house or building