Tepefy means to make something tepid.
Now, is there any reason at all why you might want to tepefy something?
Even those rare things that need to be tepid (like rising bread and...er...a baby's bottle) aren't described as tepid, are they. We say blood-hot, or talk of something being lukewarm.
The only thing that's described as tepid is the reception of a dull play, and that's something which, by definition, is hardly ever mentioned.
Tepid must be just about the limpest and drippiest word in the English language.
And tepefy is pompous, with it.
Away with them!
Word Not To Use Today: tepid and tepify. These words come from the Latin tepidus, from tepēre, to be lukewarm.