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lukewarm; tepid
half-hearted; vague; weak
lenient; mild; soft
生ぬるい温度のコーヒーは飲む気になれず淹れ直した。
I didn't feel like drinking the lukewarm coffee, so I brewed a fresh cup.
問題への生ぬるい対応が事態をさらに悪化させてしまう。
A half-hearted response to the problem will only make things worse.
自販機で買ったお茶がすでに生ぬるかった。
The tea I bought from the vending machine was already lukewarm.