There are many different words which can be used as synonyms for the word "organism". Some examples of these synonyms include "creature", "living being", "living thing", "animal", "plant", "being", and "entity". Each of these words is used to describe living things in different contexts, and can be used to describe everything from microbes and insects, to trees and animals. Some of these terms may be more common in scientific contexts, while others may be used more commonly in everyday conversation. Ultimately, the word you choose will depend on the specific context in which you are discussing living things.