To break or separate (something) into its constituent parts or elements, especially by chemical means.
Electrolysis can be used to decompose water into hydrogen and oxygen.
To rot or decay through the action of bacteria and fungi.
The fruit started to decompose after being left out in the sun for too long.
Mathematics: To express (a quantity such as a number, function, or vector) as a sum, product, or other combination of simpler or more fundamental components.
Using Fourier analysis, engineers decompose the signal into its constituent frequencies.