n. Chemical symbol, S; atomic weight, 31.98. An elementary substance which occurs in nature as a brittle crystalline solid, with resinous luster, almost tasteless, and emitting when rubbed or warmed a peculiar characteristic odor.n. The supposed substance of lightning.n. In zoology, one of many different pieridine butterflies: a yellow pierian.Of the color of brimstone, or stick-sulphur; of a very greenish, excessively luminous, and highly chromatic yellow: used in zoölogy in many obvious compounds: as, sulphur-bellied; sulphur-crested.To apply sulphur to; also, to fume with sulphur;, sulphurate.n.