1. A plant living on dead or decaying matter.
2. Any vegetable organism that lives on decayed organic matter.
3. A saprotrophic organism; especially, a fungus or microorganism.
4. An organism, especially a fungus or bacterium, that grows on and derives its nourishment from dead or decaying organic matter that help natural decomposition of organic matter in water.
5. An organism that derives its nourishment by absorbing the products or remains of other organisms.

Many fungi and bacteria are saprophytes and are important in food chains in returning nutrients to the soil by means of putrefaction and decay.