The Collaborative International Dictionary of English v.0.48:

Magpie \Mag"pie\, n. [OE. & Prov. E. magot pie, maggoty pie, fr.
   Mag, Maggot, equiv. to Margaret, and fr. F. Marquerite, and
   common name of the magpie. Marguerite is fr. L. margarita
   pearl, Gr. ?, prob. of Eastern origin. See Pie magpie, and
   cf. the analogous names Tomtit, and Jackdaw.] (Zool.)
   Any one of numerous species of the genus Pica and related
   genera, allied to the jays, but having a long graduated tail.
   [1913 Webster]

   2. Any one of several black-and-white birds, such as
      Gymnorhina tibicen, not belonging to the genus Pica.
      [PJC]

   Note: The common European magpie (Pica pica, or Pica
         caudata) is a black and white noisy and mischievous
         bird. It can be taught to speak. The American magpie
         (Pica Hudsonica) is very similar. The yellow-belled
         magpie (Pica Nuttalli) inhabits California. The blue
         magpie (Cyanopolius Cooki) inhabits Spain. Other
         allied species are found in Asia. The Tasmanian and
         Australian magpies are crow shrikes, as the white
         magpie (Gymnorhina organicum), the black magpie
         (Strepera fuliginosa), and the Australian magpie
         (Cracticus picatus).
         [1913 Webster]

   3. A talkative person; a chatterbox.
      [PJC]

   Magpie lark (Zool.), a common Australian bird (Grallina
      picata), conspicuously marked with black and white; --
      called also little magpie.

   Magpie moth (Zool.), a black and white European geometrid
      moth (Abraxas grossulariata); the harlequin moth. Its
      larva feeds on currant and gooseberry bushes.
      [1913 Webster]

WordNet (r) 3.0 (2006):

magpie
    n 1: long-tailed black-and-white crow that utters a raucous
         chattering call
    2: someone who collects things that have been discarded by
       others [syn: magpie, scavenger, pack rat]
    3: an obnoxious and foolish and loquacious talker [syn:
       chatterer, babbler, prater, chatterbox, magpie,
       spouter]

Moby Thesaurus II by Grady Ward, 1.0:

328 Moby Thesaurus words for "magpie":
   Audubon warbler, Canada goose, English sparrow, accumulator,
   adjutant bird, agreeable rattle, albatross, all sorts, argala,
   assemblage, assortment, auk, auklet, avocet, babbler, bald eagle,
   baldpate, bank swallow, barbet, barn owl, barn swallow,
   barnacle goose, big talker, bill collector, bittern, blab, blabber,
   blabberer, blabbermouth, blackbird, blackcap, blatherer, blue jay,
   booby, broad spectrum, bullfinch, bunting, bush wren, bushtit,
   butcher bird, buzzard, canary, canvasback, capercaillie, caracara,
   cardinal, cassowary, catbird, cattle egret, chaffinch, chat,
   chatterbox, chatterer, chewink, chickadee, chicken hawk,
   chimney swift, chipping sparrow, cliff swallow, cockatiel,
   cockatoo, collection agent, collector, condor, conglomeration,
   connoisseur, coot, cormorant, cowbird, crake, crane, creeper,
   crossbill, crow, cuckoo, curlew, cushat, dipper, dodo, douanier,
   dove, duck, dunlin, dunner, eagle, egret, eider duck, emu, erne,
   exciseman, falcon, farmer, finch, flamingo, flicker, flycatcher,
   frigate bird, fulmar, gabber, gabbler, gallimaufry, gannet,
   garganey, gasbag, gatherer, gibble-gabbler, goldeneye, goldfinch,
   goose, great talker, greylag goose, grosbeak, grouse, guillemot,
   guinea fowl, gull, gyrfalcon, harrier, hash, hawk, hawk owl,
   hermit thrush, heron, hobby, hodgepodge, honker, hoopoe, hoot owl,
   horned owl, hot-air artist, hotchpot, hotchpotch, house finch,
   house martin, hummingbird, ibis, idle chatterer, indigo bunting,
   jabberer, jackdaw, jay, jumble, junco, jungle fowl, kea, kestrel,
   killdee, killdeer, kingbird, kingfisher, kinglet, kite, kittiwake,
   kiwi, kookaburra, lammergeier, lapwing, lark, laughing jackass,
   linnet, loon, macaw, mallard, marabou, martin, mash, mavis, medley,
   melange, merganser, merl, mess, mew, mingle-mangle, miscellany,
   miser, mishmash, mix, mixed bag, mockingbird, moulin a paroles,
   mud hen, murre, mute swan, myna, myna bird, night-heron, nighthawk,
   nightingale, nightjar, nutcracker, nuthatch, odds and ends, olio,
   olla podrida, omnium-gatherum, oriole, ortolan, osprey, ostrich,
   ouzel, owl, oyster catcher, pack rat, parakeet, parrot, partridge,
   passenger pigeon, pasticcio, pastiche, patchwork, patterer,
   peafowl, peewee, pelican, penguin, petrel, phalarope, pheasant,
   phoebe, pigeon, plover, potpourri, prater, prattler, ptarmigan,
   puffin, rail, rattle, raven, razorbill, red grouse, redbird,
   redhead, redpoll, redshank, redstart, redwing, rhea, ring ouzel,
   ringdove, ringtail, robin, rook, ruddy duck, salad, salmagundi,
   sapsucker, sauce, scarlet tanager, scaup duck, scramble,
   screech owl, sea duck, sea eagle, sea gull, sea mew, sea swallow,
   secretary bird, sheldrake, shoebill, shoebird, shrike, siskin,
   snipe, snow bunting, snowbird, solan goose, song sparrow,
   song thrush, songbird, sparrow, sparrow hawk, spoonbill, sprig,
   starling, stew, stilt, stork, storm petrel, stormy petrel, swallow,
   swan, swan goose, swift, tanager, tax collector, teal, teal duck,
   tern, thrasher, thrush, tit, toucan, towhee, tragopan,
   tree swallow, trumpeter, turkey, turnstone, turtledove, veery,
   vulture, warbler, waxwing, weaver, weaverbird, what you will,
   whippoorwill, whistler, widgeon, wild duck, willet, windbag,
   windjammer, wood duck, wood owl, wood pigeon, woodcock, woodpecker,
   word-slinger, wren, wryneck, yellowbird, yellowhammer, yellowlegs,
   yellowthroat, zebra finch



The Devil's Dictionary (1881-1906):

MAGPIE, n.  A bird whose thievish disposition suggested to someone
that it might be taught to talk.