Scale1  —n. 1 each of the thin horny plates protecting the skin of fish and reptiles. 2 something resembling this. 3 white deposit formed in a kettle etc. By hard water. 4 tartar formed on teeth. —v. (-ling) 1 remove scale(s) from. 2 form or come off in scales.  scaly adj. (-ier, -iest). [french escale]