WordNet (r) 3.0 (2006):

irrupt
    v 1: enter uninvited; "They intruded on our dinner party"; "She
         irrupted into our sitting room" [syn: intrude, irrupt]
    2: erupt or intensify suddenly; "Unrest erupted in the country";
       "Tempers flared at the meeting"; "The crowd irrupted into a
       burst of patriotism" [syn: erupt, irrupt, flare up,
       flare, break open, burst out]
    3: increase rapidly and in an uncontrolled manner; "The
       population of India is exploding"; "The island's rodent
       population irrupted" [syn: explode, irrupt]

Moby Thesaurus II by Grady Ward, 1.0:

123 Moby Thesaurus words for "irrupt":
   admit, advance upon, arise, barge in, be admitted, be born, become,
   belch, bob up, break bounds, break forth, break in, break in upon,
   break out, breeze in, burst forth, burst in, bust in, butt in,
   charge in, come barging in, come between, come breezing in,
   come busting in, come forth, come in, come out, come to be, crash,
   crash in, crash the gates, creep in, crop up, cross the threshold,
   crowd in, cut in, debouch, disgorge, drop in, edge in, eject,
   elbow in, encroach, enter, entrench, eruct, erupt, expel, flare up,
   flash, foist in, gain admittance, get in, get to be, gleam, go in,
   go into, go too far, have an entree, have an in, have origin,
   hop in, horn in, impinge, impose, impose on, impose upon,
   infiltrate, infringe, insert, insinuate, interfere, interlope,
   interpose, intervene, intrude, invade, issue, issue forth, jam in,
   jump in, know no bounds, look in, make an inroad, obtrude,
   originate, overstep, overstep the bounds, pack in, pop in, pop up,
   press in, push in, put in, put on, put upon, rise, rush in,
   set foot in, slink in, slip in, smash in, sneak in, spew,
   spring up, squeeze in, start up, steal in, step in, storm in,
   take birth, take in, take rise, throng in, thrust in, transgress,
   trench, trespass, usurp, visit, wedge in, work in, worm in