Something, especially a liquid, that is lukewarm is only slightly warm.
tepid
Wash your face with lukewarm water.
用温水洗脸。
If you describe a person or their attitude as lukewarm, you mean that they are not showing much enthusiasm or interest.
Economists have never been more than lukewarm towards him.
经济学家们从未对他产生过什么兴趣。