Step 1: Understand the word.
Taciturn means habitually silent, saying very little - reserved, laconic, quiet.
Step 2: Identify the antonym.
The opposite of rarely speaking is speaking a great deal.
Step 3: Confirm.
Silent, reserved, and laconic are all synonyms of taciturn. Talkative - fond of talking freely - is the direct opposite and the correct antonym.
\[ \boxed{\text{talkative}} \]