General alternatives:
* Equivalent: This is a very close synonym for "synonym," implying a word with the same meaning.
* Paraphrase: This refers to rephrasing a word or phrase using different words, but conveying the same meaning.
* Substitute: This word emphasizes the ability to replace one word with another without changing the meaning.
* Analogue: This term implies a similarity in meaning, but not necessarily an exact equivalence.
* Counterpart: This word is often used when comparing words from different languages that have similar meanings.
More specific alternatives:
* Near synonym: This describes a word that has a similar meaning, but with subtle differences in nuance.
* Antonym: This refers to a word with the opposite meaning. While not a synonym, it's a related term.
* Homonym: This is a word that is spelled or pronounced the same as another word but has a different meaning.
The best alternative for "synonym" will depend on the context and the specific meaning you wish to convey.