[1] : WordNet (r) 2.0

sit down
     v 1: take a seat syn: sit ant: arise
     2: show to a seat; assign a seat for; "the host seated me next
        to mrs. smith" syn: seat, sit
     3: be seated syn: sit ant: stand, lie
see also:
sit arise seat stand lie 

[2] : Moby Thesaurus II by Grady Ward, 1.0

55 moby thesaurus words for "sit down":
   anchor, be seated, billet at, bivouac, boycott, burrow, camp,
   colonize, come to anchor, domesticate, drop anchor, ensconce,
   establish residence, go on strike, go out, hive, hold out, inhabit,
   keep house, light, live at, locate, lock out, moor, move, nest,
   park, people, perch, picket, populate, relocate, remain seated,
   reside, revolt, roost, set, set down, set up housekeeping,
   set up shop, settle, settle down, shut it down, sit, slow down,
   squat, stand, stay at, strike, strike root, take residence at,
   take root, take up residence, touch down, walk out

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