Main Entry: sul·fur

Variant(s): also sul·phur \ˈsəl-fər\

Function: noun

Etymology: Middle English sulphur brimstone, from Latin sulpur, sulphur, sulfur

Date: 14th century

: a nonmetallic element that occurs either free or combined especially in sulfides and sulfates, is a constituent of proteins, exists in several allotropic forms including yellow orthorhombic crystals, resembles oxygen chemically but is less active and more acidic, and is used especially in the chemical and paper industries, in rubber vulcanization, and in medicine for treating skin diseases — see element table

— sul·fury or sul·phury \-ē\ adjective

usage The spelling sulfur predominates in United States technical usage, while both sulfur and sulphur are common in general usage. British usage tends to favor sulphur for all applications. The same pattern is seen in most of the words derived from sulfur.