sulfur

noun

sul·​fur ˈsəl-fər 

variants or chiefly British sulphur

: a nonmetallic chemical element that is an essential element for all life, resembles oxygen in chemical properties, and is used especially in the form of sulfuric acid to extract phosphates from ores see Chemical Elements Table

sulfury adjective

or chiefly British sulphury

ˈsəl-fər-ē 

Is it sulfur or sulphur?: Usage Guide

The spelling sulfur predominates in U.S. 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.

Examples of sulfur in a Sentence

Recent Examples on the Web

Dual‑level engineering of metal–organic framework Taking on this challenge, the team showcased dual‑level engineering of metal–organic framework (MOF)‑derived hierarchical porous carbon nanofibers for high‑performance lithium–sulfur batteries. —Prabhat Ranjan Mishra, Interesting Engineering, 8 Nov. 2025

Those flies themselves depend on sulfur-oxidizing microbes as their primary food source. —Humberto Basilio, Scientific American, 7 Nov. 2025

The sulfur-rich stream, fed by natural springs and winds through the cavern, releases hydrogen sulfide that sustains this unexpected chain of life. —Alice Gibbs, MSNBC Newsweek, 5 Nov. 2025

Here, sulfur-oxidizing bacteria grow in thick white biofilms on wet rock and sediment. —New Atlas, 5 Nov. 2025

Word History

Etymology

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

First Known Use

14th century, in the meaning defined above

Phrases Containing sulfur

• sulfur bacterium
• sulfur dioxide
• sulfur mushroom
• sulfur polypore
• sulfur shelf

Rhymes for sulfur

• sulphur

Kids Definition

sulfur

noun

sul·​fur

variants also sulphur

ˈsəl-fər 

: a nonmetallic element that occurs either free or combined especially in sulfides and sulfates, is found in proteins, exists in several forms including yellow crystals, and is used especially in the chemical and paper industries, in strengthening rubber, and in medicine for treating skin diseases see element

Medical Definition

sulfur

1 of 2 noun

sul·​fur

variants or chiefly British sulphur

ˈsəl-fər 

: 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

—symbol S see Chemical Elements Table

sulfur

2 of 2 adjective

variants or chiefly British sulphur

: of, relating to, or resembling sulfur : containing or impregnated with sulfur