The Collaborative International Dictionary of English v.0.48:

Thread \Thread\ (thr[e^]d), n. [OE. threed, [thorn]red, AS.
   [thorn]r[=ae]d; akin to D. draad, G. draht wire, thread, OHG.
   dr[=a]t, Icel. [thorn]r[=a][eth]r a thread, Sw. tr[*a]d, Dan.
   traad, and AS. [thorn]r[=a]wan to twist. See Throw, and cf.
   Third.]
   1. A very small twist of flax, wool, cotton, silk, or other
      fibrous substance, drawn out to considerable length; a
      compound cord consisting of two or more single yarns
      doubled, or joined together, and twisted; also, one fiber
      of a cord composed of multiple fibers.
      [1913 Webster]

   2. A filament of any substance, as of glass, gold or silver;
      a filamentous part of an object, such as a flower; a
      component fiber of any or of any fibrous substance, as of
      bark.
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   3. The prominent part of the spiral of a screw or nut; the
      rib. See Screw, n., 1.
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   4. (Fig.) Something continued in a long course or tenor; a
      recurrent theme or related sequence of events in a larger
      story; as the thread of a story, or of life, or of a
      discourse. --Bp. Burnet.
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   5. Fig.: Composition; quality; fineness. [Obs.]
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            A neat courtier,
            Of a most elegant thread.             --B. Jonson.
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   6. (Computers) A related sequence of instructions or actions
      within a program that runs at least in part independent of
      other actions within the program; -- such threads are
      capable of being executed only in oprating systems
      permittnig multitasking.
      [PJC]

   7. (Computers) A sequence of messages posted to an on-line
      newsgroup or discussion group, dealing with the same
      topic; -- messages in such a thread typically refer to a
      previous posting, thus allowing their identification as
      part of the thread. Some news-reading programs allow a
      user to follow a single such thread independent of the
      other postings to that newsgroup.
      [PJC]

   Air thread, the fine white filaments which are seen
      floating in the air in summer, the production of spiders;
      gossamer.

   Thread and thrum, the good and bad together. [Obs.] --Shak.

   Thread cell (Zool.), a lasso cell. See under Lasso.

   Thread herring (Zool.), the gizzard shad. See under
      Gizzard.

   Thread lace, lace made of linen thread.

   Thread needle, a game in which children stand in a row,
      joining hands, and in which the outer one, still holding
      his neighbor, runs between the others; -- called also
      thread the needle.
      [1913 Webster]