subingression means the act of ingressing or entering subtly or unobservedly. Lexicurio rates it Sui generis — a strength score of 87 out of 100.
Etymology
From sub- + ingression.
noun
- The act of ingressing or entering subtly or unobservedly.“[T]vvo very volatile Liquors, vvhich being gently put together are as clear as Rock-vvater, and yet vvill almoſt in a moment, vvithout the ſub-ingreſſion of Air to turn them into Bubbles, ſo alter the diſpoſition of their inſenſible parts, as to become a vvhite and conſiſtent Body.”