The Collaborative International Dictionary of English v.0.48:

Blinker \Blink"er\, n.
   1. One who, or that which, blinks.
      [1913 Webster]

   2. A blinder for horses; a flap of leather on a horse's
      bridle to prevent him from seeing objects as his side
      hence, whatever obstructs sight or discernment.
      [1913 Webster]

            Nor bigots who but one way see,
            through blinkers of authority.        --M. Green.
      [1913 Webster]

   3. pl. A kind of goggles, used to protect the eyes form
      glare, etc.
      [1913 Webster]

WordNet (r) 3.0 (2006):

blinker
    n 1: a light that flashes on and off; used as a signal or to
         send messages [syn: blinker, flasher]
    2: a blinking light on a motor vehicle that indicates the
       direction in which the vehicle is about to turn [syn:
       blinker, turn signal, turn indicator, trafficator]
    3: blind consisting of a leather eyepatch sewn to the side of
       the halter that prevents a horse from seeing something on
       either side [syn: winker, blinker, blinder]
    v 1: put blinders on (a horse)

Moby Thesaurus II by Grady Ward, 1.0:

72 Moby Thesaurus words for "blinker":
   Roman candle, aid to navigation, alarm, amber light, balefire,
   beacon, beacon fire, bell, bell buoy, blue peter, buoy,
   caution light, flare, fog bell, fog signal, fog whistle, foghorn,
   glance, go light, gong buoy, green light, heliograph, high sign,
   international alphabet flag, international numeral pennant, kick,
   leer, marker beacon, nod, nudge, parachute flare, pilot flag, poke,
   police whistle, quarantine flag, radio beacon, red flag, red light,
   rocket, sailing aid, semaphore, semaphore flag,
   semaphore telegraph, 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, spar buoy, stop light, the nod,
   the wink, touch, traffic light, traffic signal, watch fire,
   white flag, wigwag, wigwag flag, wink, yellow flag