Decompose meaning 1, decay, become rotten. 2, Break down into component elements (Oxford University press,2002: 264)
Decomposition (verb) is the process by which organic substances are broken down into a more simple organic matter. The process is a part of the nutrient cycle and is essential for recycling the finite matter that occupies physical space in the biosphere. Bodies of living organisms begin to decompose shortly after death.
Environmental factors also change the process of decomposition, it is extremely important that a make-up artist is aware of these factor when recreating a decomposition look. figure one is a great medical referencing website where medical professionals from all around the world update with pictures and factual information. Here is a link to Figure1 https://figure1.com/ .