lukewarm or halfhearted
tepid - lukewarm
The word ‘tepid’ can be used in relation to a liquid that is not very warm, or something that is lacking in interest, emotion, or enthusiasm. It has negative connotations as people typically do not want a tepid liquid, and certainly would not like a tepid response to something they have said or done.
My suggestion only received a tepid response, so I don’t think it will be taken under consideration.
I’m going to ask for another coffee. The one they served me is already tepid.
Frank’s heart is clearly not in teaching anymore. There has been a certain tepidness to his approach for a while now.