- The definition of a decomposer is an organism that causes organic material to break down or decompose.
A worm that causes compost to break down is an example of a decomposer.
decomposer definition by American Heritage Dictionary
The American Heritage® Dictionary of the English Language, 4th edition Copyright © 2010 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
An organism, often a bacterium or fungus, that feeds on and breaks down dead plant or animal matter, thus making organic nutrients available to the ecosystem.
decomposer - Science Definition