Decompose, v. t. [imp. & p. p. Decomposed; p. pr. & vb. n. Decomposing.]
Etymology: [Cf. F. décomposer. Cf. Discompose.]
To separate the constituent parts of; to resolve into original elements; to set free from previously existing forms of chemical combination; to bring to dissolution; to rot or decay.
1 other Webster entry under this spelling
Decompose, v. i.
To become resolved or returned from existing combinations; to undergo dissolution; to decay; to rot.
Shades of meaning
Fernald has no entry of its own for decompose; he lists it under decay.
Where he writes about it:
Rot is a strong word, ordinarily esteemed coarse, but on occasion capable of approved emphatic use; as, "the name of the wicked shall rot," Prov. x, 7; decay and decompose are now common euphemisms. — from decay