General Antonyms:
* Apathetic: Lacking interest or enthusiasm.
* Indifferent: Not caring one way or the other.
* Lukewarm: Showing little enthusiasm or interest.
* Passive: Accepting or allowing what happens without active response or resistance.
* Tepid: Showing or feeling little enthusiasm; halfhearted.
Antonyms in Specific Contexts:
* Cold (emotionally): Used to describe someone who lacks warmth or affection.
* Detached (emotionally): Removed from emotion or feeling.
* Doubtful (belief): Holding a lack of belief or certainty.
* Unconcerned (attitude): Not worried or bothered about something.
* Unenthusiastic (attitude): Lacking enthusiasm or excitement.
* Uninterested (attitude): Not finding something engaging or appealing.
The best antonym for "fervent" will depend on the specific context in which you are using the word.