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
It is an opposite meaning of enthusiastic. A type of scepticism. If someone doesn't believe in success.
by iGame_again April 3, 2016
(n.) a person who is unenthusiastic about everything and defines their personal by such an intense lack of enthusiasm
by Rambler369 December 20, 2021