The Collaborative International Dictionary of English v.0.48:

Nudge \Nudge\ (n[u^]j), v. t. [imp. & p. p. Nudged (n[u^]jd);
   p. pr. & vb. n. Nudging.] [Cf. Prov. G. kn["u]tschen to
   squeeze, pinch, E. Knock.]
   To touch gently, as with the elbow, in order to call
   attention or convey intimation.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Nudge \Nudge\, n.
   A gentle push, or jog, as with the elbow.
   [1913 Webster]

WordNet (r) 3.0 (2006):

nudge
    n 1: a slight push or shake [syn: nudge, jog]
    v 1: to push against gently; "She nudged my elbow when she saw
         her friend enter the restaurant" [syn: nudge, poke at,
         prod]
    2: push into action by pestering or annoying gently

Moby Thesaurus II by Grady Ward, 1.0:

223 Moby Thesaurus words for "nudge":
   Roman candle, actuate, aid to navigation, alarm, amber light,
   assault, attouchement, balefire, beacon, beacon fire, bear,
   bear upon, bearing, beat the drum, bell, bell buoy, blinker,
   blue peter, boost, bring to recollection, broad hint, brush,
   brush by, buck, bull, bulldoze, bump, bump against, bunt, buoy,
   butt, butt against, caress, carry back, caution light, clue,
   come in contact, contact, contingence, cram, crowd, cue, dig, dip,
   drive, elbow, encourage, encouragement, exchange colors, flag,
   flag down, flare, flash, flog, fog bell, fog signal, fog whistle,
   foghorn, force, gentle hint, gesture, give a hint, give a signal,
   give the cue, give the nod, glance, glimmer, glimmering, go light,
   goad, gong buoy, graze, green light, hail, hail and speak,
   half-mast, head, heliograph, high sign, hint, hit, hoist a banner,
   hold the promptbook, hurtle, hustle, impel, impinge, impingement,
   impingence, implication, index, indication, inkling, innuendo,
   insinuation, international alphabet flag,
   international numeral pennant, intimation, jab, jam, jog,
   jog the memory, joggle, jolt, jostle, kick, kiss, lash, leer, look,
   make a sign, marker beacon, mobilize, motivate, move, nag, needle,
   nod, osculate, osculation, parachute flare, pile drive, pilot flag,
   poke, police whistle, press, pressure, prick, prod, prompt,
   prompt the mind, propel, punch, push, put in mind,
   put in remembrance, quarantine flag, radio beacon, raise a cry,
   ram, ram down, rattle, recall, red flag, red light, remember,
   remind, remind one of, rocket, rub, run, run against, sailing aid,
   salute, scent, scrape, semaphore, semaphore flag,
   semaphore telegraph, set in motion, shake, shave, shoulder, shove,
   sideswipe, sign, signal, signal beacon, signal bell, signal fire,
   signal flag, signal gong, signal gun, signal lamp, signal light,
   signal mast, signal post, signal rocket, signal shot, signal siren,
   signal tower, signalize, skim, skirt, sound an alarm,
   sound the trumpet, spar buoy, speak, spoor, spur, squeak by, sting,
   stop light, stress, suggest, suggestion, suspicion, symptom,
   taction, tamp, tangency, telltale, tentative contact, the nod,
   the wink, thrust, touch, touching, track, traffic light,
   traffic signal, unfurl a flag, watch fire, wave, wave a flag,
   wave the hand, whip, whisper, white flag, wigwag, wigwag flag,
   wink, yellow flag