Putrescent means rotting or decaying, especially when something organic is breaking down and starting to smell terrible. When food goes bad in the back of the refrigerator for weeks, it becomes putrescent: moldy, smelly, and disgusting. A pumpkin left on the porch long after Halloween turns putrescent as it collapses into mush.

Scientists studying decomposition might describe a putrescent sample, while a health inspector might condemn putrescent food at a restaurant. You might read about putrescent conditions in a story about medieval dungeons or abandoned buildings.

While decay is a natural and important part of nature's recycling system (returning nutrients to the soil), putrescent specifically captures the stage when something is actively rotting and truly revolting. It's a strong word that writers use when “rotten” or “spoiled” doesn't quite capture how thoroughly something has decomposed. If you encounter something putrescent, your nose will tell you immediately, and you'll want to get away fast.