It is an opposite meaning of enthusiastic. A type of scepticism. If someone doesn't believe in success.
by iGame_again April 03, 2016
It’s an adjective and it means not having or lacking enthusiasm. If someone is unenthusiastic about something it means they are feeling indifferent, apathetic, passive, phlegmatic, lukewarm, listless, languid, lethargic, emotionless, perfunctory about it.
by AKACroatalin March 24, 2017
(n.) a person who is unenthusiastic about everything and defines their personal by such an intense lack of enthusiasm
by Rambler369 December 20, 2021