Sulfurous describes something that contains sulfur or smells like sulfur. Sulfur is a yellow chemical element that creates a distinctive sharp, unpleasant odor when it burns, like rotten eggs or struck matches.

You might encounter sulfurous smells near hot springs or volcanoes, where sulfur naturally seeps up from deep in the earth. The “rotten egg” smell in stink bombs comes from sulfurous compounds. Coal and oil contain sulfur, so when they burn, they can release sulfurous gases into the air.

In older writing, you'll sometimes see sulfurous used to describe something hellish or fiery, since people once imagined hell filled with burning sulfur (sometimes called brimstone). A character might describe a villain's sulfurous temper, meaning it's hot, dangerous, and explosive.

The word can also appear in chemistry class, where sulfurous acid is a specific chemical compound. Scientists might describe sulfurous fumes from an experiment, warning others to work in a well-ventilated area.

You might also see the alternate spelling sulphurous, which means exactly the same thing but uses the British spelling of sulfur, sulphur.