The Hebrew word for word is מילה , which derives from the Aramaic root מ.ל.ל meaning speech.
מילה is a feminine word, even though it doesn’t appear to be one in the plural: words are מילים .
A synonym is מילה נרדפת – literally, a word chased/pursued (by another word, perhaps trying to catch up).
יחסית לאנגלית, אין הרבה מילים נרדפות בעברית.
Relative to English, there aren’t many synonyms in Hebrew.
Another way of saying (a synonym for) synonym is שם נרדף – a chased/pursued name.