illapse
A gliding in; an immission or entrance of one thing into another.
rare
Now it is certain, that no Man was more poſitive, as to the Conſecration of the Holy Euchariſt by the Illapſe of the Holy Spirit, than St. Chrysoſtom; and therefore the Reaſon, why he did not come into the Meaſures of Theophilus, muſt be, that he was not convinced, that Origen was guilty of that Error, which Theophilus, and his Friends, imputed to him.
A sudden descent or attack.
rare
[…] That as a piece of Iron red hot by reaſon of the Illapſe of the fire into it appears all over like fire; ſo the Souls of the Bleſſed by this Illapſe of the Divine Eſſence into them ſhall be all over Divine.
Where it comes from
From Latin illapsus (“a falling, gliding, or flowing in; an irruption”); from illābor (“to fall, to slide”) + -tus (“suffix forming action nouns from verbs”).
Adapted from the Wiktionary entry illapse (CC BY-SA 4.0).