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

Chill onions for 10 to 15 minutes in the refrigerator or 5 minutes in the freezer to help slow down the release of sulfur compounds when cutting. Grab a sharp knife: A sharp knife cuts through cleanly, while a dull knife does more damage to the onion cells, releasing more gas. —Katie Rosenhouse, Southern Living, 16 May 2025

Products marketed as azalea fertilizers do supply nutrients needed by the plants that can help offset the effects of an improper pH. Use of soil-acidifying products like soil sulfur treatments and a pine bark fines mulch can also help when the soil is not suitable for acid-loving azaleas. —Tom MacCubbin, The Orlando Sentinel, 10 May 2025

The rover ran over and broke open a stunning rock full of yellow sulfur crystals last year. —Amanda Kooser, Forbes.com, 9 May 2025

This super-concentrated spot corrector comprises 10% sulfur and lightly exfoliating glycolic acid and oil-controlling niacinamide, which dry out zits and prevent new ones from cropping up. —Annie Blackman, Allure, 5 May 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