(with reference to a dead body or other organic matter) make or become rotten; decay or cause to decay: [no object]:the body had begun to decompose (as adjective decomposing)decomposing fungi [with object]:dead plant matter can be completely decomposed by micro-organisms
(with reference to a chemical compound) break down or cause to break down into component elements or simpler constituents: [no object]:many chemicals decompose rapidly under high temperature [with object]:living organisms are used to decompose water into hydrogen and oxygen
[with object] Mathematics express (a number or function) as a combination of simpler components:in how many ways can one decompose a number as a sum of squares?