The term "decomposes" refers to the process of breaking down organic matter into simpler substances. The opposite of this process is "composes," which means to create or put together. Another antonym for "decomposes" is "preserves" or "conserves," which involves preventing the breakdown of organic matter. "Recomposes" can also serve as an antonym of "decomposes", which means to assemble or construct something after disassembling. Additionally, "builds up" can be used as an antonym in the context of organic matter, indicating the formation of new material rather than its deterioration. Other antonyms for "decomposes" may include "enlivens," "animates," or "revives," which involve bringing life or energy to something rather than allowing it to break down.