Answer:
a. A word that has the same meaning as another
Explanation:
A synonym is a word that has the same meaning as another, like "to end" and "to finish".
These are very useful when you write a text and want to avoid repeating the same word over and over. Just have to be careful though, because synonyms have the same general meaning... but each word has a specific meaning, that's why it was created in the first place.
Option B, a word that has the opposite meaning as another, is an antonym, not a synonym.
