LOQUACIOUS: Talkative.
1.Tranquil: calm and peaceful and without noise, violence, worry etc.
2.Skeptical: a person who doubts the truth or value of an idea or belief
3.Morose: unhappy, annoyed, and unwilling to speak or smile (in a negative way)
4.Taciturn: tending not to speak much
5.Witty: using words in a clever and funny way
The answer would be 4.Taciturn. It is the most opposite meaning in to the given word.