The Collaborative International Dictionary of English v.0.48:

Sidle \Si"dle\, v. t. [imp. & p. p. Sidled; p. pr. & vb. n.
   Sidling.] [From Side.]
   To go or move with one side foremost; to move sidewise; as,
   to sidle through a crowd or narrow opening. --Swift.
   [1913 Webster]

         He . . . then sidled close to the astonished girl.
                                                  --Sir W.
                                                  Scott.
   [1913 Webster]

WordNet (r) 3.0 (2006):

sidle
    v 1: move unobtrusively or furtively; "The young man began to
         sidle near the pretty girl sitting on the log"
    2: move sideways [syn: sidle, sashay]

Moby Thesaurus II by Grady Ward, 1.0:

199 Moby Thesaurus words for "sidle":
   accost, advance, amble, approach, appropinquate, approximate,
   ascend, avert, bank, barge, bear down on, bear down upon, bear off,
   bear up, bowl along, bundle, cant, careen, climb, close, close in,
   close with, clump, come, come closer, come forward, come near,
   come on, come up, confront, crawl, creep, decline, descend, dip,
   drag, draw aside, draw near, draw nigh, droop, drop, ease,
   ease off, edge, edge off, encounter, fall, fall away, fall off,
   flounce, fly off, foot, footslog, gain upon, gait, gallop, gee,
   glance, glance off, go crabwise, go downhill, go off, go on tiptoe,
   go sideways, go uphill, grade, grovel, gumshoe, halt, haw,
   head off, hippety-hop, hitch, hobble, hop, inch, inch along,
   incline, jib, jog, jolt, jump, keel, lateral, lateralize, lean,
   limp, list, lock step, lumber, lunge, lurch, make leeway,
   make way for, mince, mincing steps, move aside, narrow the gap,
   near, nightwalk, pace, pad, paddle, peg, piaffe, piaffer, pitch,
   plod, prance, prowl, proximate, pussyfoot, rack, rake, retreat,
   rise, roll, sashay, saunter, scrabble, scramble, scuff, scuffle,
   scuttle, shamble, sheer off, shelve, shove aside, shuffle, shunt,
   shy, shy off, side, sideslip, sidestep, sidetrack, sidle up to,
   single-foot, skew, skid, skip, slant, slink, slip, slither, slog,
   slope, slouch, slowness, snake, sneak, stagger, stalk, stamp,
   steal, steal along, steer clear of, step, step aside, step up,
   stomp, straddle, straggle, stride, stroll, strolling gait, strut,
   stump, swag, swagger, sway, swing, switch, tilt, tip, tippytoe,
   tiptoe, tittup, toddle, totter, traipse, tread, trip, trot, trudge,
   turn aside, turn away, turn back, uprise, veer, veer off, velocity,
   waddle, walk, wamble, wiggle, wobble, worm, worm along