Three of the following four words are alike in a certain way and one is different. Select the odd one.

Contention Turmoil Conflict Tranquility

Tranquility

Except Tranquility all are synonyms of each other Contention , Turmoil , Conflict all are synonyms of each other Tranquility is the antonym Contention - heated disagreement Conflict- disturbance Turmoil - confusion , Tranquility - calm