See Ormus.
So Dems ragging on how infest is racist lured me to the dictionary again.
In-fest
infest (v.)
late 15c., to attack, assail, hurt, distress, annoy, from Old French infester (14c.), from Latin infestare “to attack, disturb, trouble, from infestus unsafe, hostile, threatening, dangerous, originally inexorable, not able to be handled, from in- not, opposite of (see in- (1)) + -festus, perhaps (able to be) seized (see manifest (adj.)). Sense of swarm over in large numbers, attack parasitically first recorded c. 1600. Related: Infested; infesting.
Relate entries & more
infestation (n.)
early 15c., a being infested, from Old French infestacion, from Late Latin infestationem (nominative infestatio) a troubling, a disturbing, a molesting, noun of action from past participle stem of Latin infestare to attack, disturb (see infest).
in- (2)
element meaning into, in, on, upon (also im-, il-, ir- by assimilation of -n- with following consonant), from Latin in- in, from PIE root *en in.
-fest
word-forming element in colloquial compounds (hen-fest, gabfest, etc.), from 1889, American English, borrowed from German Fest festival, abstracted from Volksfest, etc., from Middle High German vëst, from Latin festum festival or holiday, neuter of festus of a feast (see feast (n.)).
in- into, in, on, upon
-fest- festival, holiday, feast