irrupt (v.)Related entries & more
"to break into," 1805 (implied in irrupted), back-formation from irruption or else from Latin irruptus, past participle of irrumpere "to break in, burst into."
irruption (n.)Related entries & more
1570s, from French irruption (14c.) or directly from Latin irruptionem (nominative irruptio) "a breaking in, bursting in, invasion," noun of action from past-participle stem of irrumpere "to break in, force one's way in, burst into," from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + rumpere (see rupture (n.)). Frequently confused with eruption.