The Collaborative International Dictionary of English v.0.48:

Thing \Thing\ (th[i^]ng), n. [AS. [thorn]ing a thing, cause,
   assembly, judicial assembly; akin to [thorn]ingan to
   negotiate, [thorn]ingian to reconcile, conciliate, D. ding a
   thing, OS. thing thing, assembly, judicial assembly, G. ding
   a thing, formerly also, an assembly, court, Icel. [thorn]ing
   a thing, assembly, court, Sw. & Dan. ting; perhaps originally
   used of the transaction of or before a popular assembly, or
   the time appointed for such an assembly; cf. G. dingen to
   bargain, hire, MHG. dingen to hold court, speak before a
   court, negotiate, Goth. [thorn]eihs time, perhaps akin to L.
   tempus time. Cf. Hustings, and Temporal of time.]
   1. Whatever exists, or is conceived to exist, as a separate
      entity, whether animate or inanimate; any separable or
      distinguishable object of thought.
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            God made . . . every thing that creepeth upon the
            earth after his kind.                 --Gen. i. 25.
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            He sent after this manner; ten asses laden with the
            good things of Egypt.                 --Gen. xiv.
                                                  23.
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            A thing of beauty is a joy forever.   --Keats.
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   2. An inanimate object, in distinction from a living being;
      any lifeless material.
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            Ye meads and groves, unconscious things! --Cowper.
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   3. A transaction or occurrence; an event; a deed.
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            [And Jacob said] All these things are against me.
                                                  --Gen. xlii.
                                                  36.
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            Which if ye tell me, I in like wise will tell you by
            what authority I do these things.     --Matt. xxi.
                                                  24.
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   4. A portion or part; something.
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            Wicked men who understand any thing of wisdom.
                                                  --Tillotson.
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   5. A diminutive or slighted object; any object viewed as
      merely existing; -- often used in pity or contempt.
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            See, sons, what things you are!       --Shak.
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            The poor thing sighed, and . . . turned from me.
                                                  --Addison.
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            I'll be this abject thing no more.    --Granville.
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            I have a thing in prose.              --Swift.
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   6. pl. Clothes; furniture; appurtenances; luggage; as, to
      pack or store one's things. [Colloq.]
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   Note: Formerly, the singular was sometimes used in a plural
         or collective sense.
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               And them she gave her moebles and her thing.
                                                  --Chaucer.
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   Note: Thing was used in a very general sense in Old English,
         and is still heard colloquially where some more
         definite term would be used in careful composition.
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               In the garden [he] walketh to and fro,
               And hath his things [i. e., prayers, devotions]
               said full courteously.             --Chaucer.
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               Hearkening his minstrels their things play.
                                                  --Chaucer.
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   7. (Law) Whatever may be possessed or owned; a property; --
      distinguished from person.
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   8. [In this sense pronounced t[i^]ng.] In Scandinavian
      countries, a legislative or judicial assembly.
      --Longfellow.
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   Things personal. (Law) Same as Personal property, under
      Personal.

   Things real. Same as Real property, under Real.
      [1913 Webster] Thing

The Collaborative International Dictionary of English v.0.48:

Thing \Thing\, Ting \Ting\, n. [Dan. thing, ting, Norw. ting, or
   Sw. ting.]
   In Scandinavian countries, a legislative or judicial
   assembly; -- used, esp. in composition, in titles of such
   bodies. See Legislature, Norway.
   [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

thing
    n 1: a special situation; "this thing has got to end"; "it is a
         remarkable thing"
    2: an action; "how could you do such a thing?"
    3: a special abstraction; "a thing of the spirit"; "things of
       the heart"
    4: an artifact; "how does this thing work?"
    5: an event; "a funny thing happened on the way to the..."
    6: a vaguely specified concern; "several matters to attend to";
       "it is none of your affair"; "things are going well" [syn:
       matter, affair, thing]
    7: a statement regarded as an object; "to say the same thing in
       other terms"; "how can you say such a thing?"
    8: an entity that is not named specifically; "I couldn't tell
       what the thing was"
    9: any attribute or quality considered as having its own
       existence; "the thing I like about her is ..."
    10: a special objective; "the thing is to stay in bounds"
    11: a persistent illogical feeling of desire or aversion; "he
        has a thing about seafood"; "she has a thing about him"
    12: a separate and self-contained entity