WordNet (r) 3.0 (2006):

set in
    v 1: enter a particular state; "Laziness set in"; "After a few
         moments, the effects of the drug kicked in" [syn: set in,
         kick in]
    2: blow toward the shore; "That gale could set in on us with the
       next high tide"
    3: become established; "winter has set in"

Moby Thesaurus II by Grady Ward, 1.0:

110 Moby Thesaurus words for "set in":
   bed, begin, blast, blast away, blast off, blow, blow a hurricane,
   blow great guns, blow over, blow up, bluster, breeze, breeze up,
   brew, come up, commence, confirm, deep-dye, define, dent, depress,
   dimple, dint, dive in, ease in, embed, engraft, engrave, entrench,
   establish, etch, fall to, fix, found, freshen, gather, get to,
   go ahead, ground, head into, huff, impact, implant, impress,
   imprint, indent, infix, infuse, ingrain, inject, inoculate,
   inscribe, insert, insinuate, interject, introduce, intromit, jam,
   jump off, kick off, lodge, notch, pack, perfuse, pipe up, pit,
   pitch in, plant, plunge into, pock, pockmark, pop in, press in,
   print, puff, punch, punch in, put in, rage, recess, root, seat,
   send off, set, set about, set back, set out, set sail, set to,
   settle, slip in, squall, stamp, start, start in, start off,
   start out, stereotype, stick in, storm, take off, tamp, throw in,
   tuck in, turn to, waft, wedge, whiff, whiffle, whip in