Etymon is a term used in linguistics to refer to the root or origin of a word or phrase. There are many different synonyms that can be used for this term, depending on the context and the specific language being studied. Some of these synonyms include proto-language, lexeme, root word, morpheme, and cognate. Each of these terms refers to a slightly different aspect of language and its development over time, but they all share a focus on the historical and linguistic origins of words and phrases. Understanding the etymon of a word can be a valuable tool for understanding its meaning and usage in different contexts.