decomposer

UK: /ˌdiːkəmˈpəʊzə/ US: (dē′kəm pō′zər)

WordReference Random House Unabridged Dictionary of American English © 2025

de•com•pos•er  (dē′kəm pō′zər), n. 

1. a person or thing that decomposes.
2. Ecology an organism, usually a bacterium or fungus, that breaks down the cells of dead plants and animals into simpler substances.

• decompose + -er¹ 1815–25

Collins Concise English Dictionary © HarperCollins Publishers::

decomposer / ˌdiːkəmˈpəʊzə/ noun

1. any organism in a community, such as a bacterium or fungus, that breaks down dead tissue enabling the constituents to be recycled to the environment