adj. extremely fervid, excited, zealous; hot or ardent with eagerness; characterized by intense emotion.
This word can mean a lot of things, but all of them relate to emotional extremity. A street preacher could be perfervid with their castigation; a dog could be perfervid in its defense of the front yard; a crying baby could be perfervid in general. Anything that makes someone lose control of themselves, for good or ill, causes them to become perfervid.
In her intelligent, sometimes perfervid, often gloomy face, it suggested a series of grace-notes introduced willfully into a bit of serious music.
—The Bird in the Box by Mary M. Mears (pub. 1910)"I don't know where I was most miserable," I rejoined, beginning to see the matter in a less perfervid light.
—A Thief in the Night: A Book of Raffles' Adventures by E. W. Hornung (pub. 1905)
Etymology, working backward:
Late Latin perfervidus (of or through heat, boiling)
Proto-Indo-European suffix root per- (of, through)
Latin fervidus (hot, boiling, vehement)
ferveo (to be hot, burning, lit. ‘I boil, burn, seethe‘)
Proto-Indo-European root bhrewh (to be hot, boiling)
Usage, according to the Google’s NGrams Viewer (may not be perfectly accurate):
For context, note that ‘the’ usually floats at ~4%.