Putting the cocoon in a cool place, a dark place, but with water, so she wasn’t dry; no, not just water, but water mixed with the sap of a certain tree, and kept tepid so that certain reactions could take place in the cocoon.
There are no more uses of "tepid" in the book.
Show samples from other sources
And that would leave Jane with her tepid tea and her bone china and these girls who could make an hour’s conversation out of nothing.
Margaret Peterson Haddix -- Uprising
Before dialing, he found it all too easy to imagine that she’d answer with only tepid enthusiasm.