No, of course no one knows what jactitation means.
Any use of the word would be pure...well, jactitation.
The thing is, jactitation means to boast. It's especially a false boast which harms someone else: I'm much better at collecting ear wax/imitating a washing machine/polishing melons than he is.
Even more especially, jactitation is pretending to be married to a particular person. Once upon a time you could be taken to court for it.
If the thought of all this falsehood worries you, then you may, sadly, find yourself doing another sort of jactitation, which is making restless movements while asleep or in a fever.
I have to admit that jactitation is rather a remarkable word.
But it's one that only a dork would use.
Word Not To Use Today: jactitation. This word comes from the Latin word jactitātiō, from jacitāre, to utter publicly, from jactitāre, to toss about.