unenthusiastic
Definitions
Showing a lack of excitement, interest, or approval.
Not having or showing a strong desire or eagerness to do something.
Examples
The students gave an unenthusiastic response when the teacher announced there would be extra homework over the weekend.
He offered an unenthusiastic shrug, clearly not interested in joining the hiking trip.
Synonyms
apathetic indifferent lukewarm disinterested halfhearted uninterested listless