Simple Definition:
A synonym is a word that means the same thing as another word. For example, the words “happy” and “joyful” are synonyms because they both mean feeling good and positive emotions.
Very Simple Definition:
A word that means the same thing as another word. It is like a different word that you can use instead of the first word. For example, the words “happy” and “joyful” are synonyms because they both mean feeling good and positive emotions.