1) Ingress 
to glide in
• (v. i.) To fall or glide; to pass; -- usually followed by into. • (v. i.) A gliding in; an immisson or entrance of one thing into another; also, a sudden descent or attack.
Il·lapse' intransitive verb [ imperfect & past participle Illapsed ; present participle & verbal noun Illapsing .] [ Latin illapsus , past participle of illabi ; prefix il- in + labi to fall, slide.] To fall...Il·lapse' noun [ Latin illapsus . See Illapse , intransitive verb ] A gliding in; an immisson or entrance of one thing into another; also, a sudden descent or attack. Akenside. « They sit silent . . . waiting for an illapse of the spirit.�...
illapse, illapsing, illapsed 1. To fall or to glide; to pass (usually followed by 'into'); such as, 'He illapsed into deep sleep.' 2. A gliding in; an immisson or entrance of one thing into another; also, a sudden descent or attack.