The Collaborative International Dictionary of English v.0.48:

Labor \La"bor\ (l[=a]"b[~e]r), n. [OE. labour, OF. labour,
   laber, labur, F. labeur, L. labor; cf. Gr. lamba`nein to
   take, Skr. labh to get, seize.] [Written also labour.]
   1. Physical toil or bodily exertion, especially when
      fatiguing, irksome, or unavoidable, in distinction from
      sportive exercise; hard, muscular effort directed to some
      useful end, as agriculture, manufactures, and like;
      servile toil; exertion; work.
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            God hath set
            Labor and rest, as day and night, to men
            Successive.                           --Milton.
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   2. Intellectual exertion; mental effort; as, the labor of
      compiling a history.
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   3. That which requires hard work for its accomplishment; that
      which demands effort.
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            Being a labor of so great a difficulty, the exact
            performance thereof we may rather wish than look
            for.                                  --Hooker.
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   4. Travail; the pangs and efforts of childbirth.
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            The queen's in labor,
            They say, in great extremity; and feared
            She'll with the labor end.            --Shak.
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   5. Any pang or distress. --Shak.
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   6. (Naut.) The pitching or tossing of a vessel which results
      in the straining of timbers and rigging.
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   7. [Sp.] A measure of land in Mexico and Texas, equivalent to
      an area of 1771/7 acres. --Bartlett.

   8. (Mining.) A stope or set of stopes. [Sp. Amer.]
      [Webster 1913 Suppl.]

   Syn: Work; toil; drudgery; task; exertion; effort; industry;
        painstaking. See Toll.
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The Collaborative International Dictionary of English v.0.48:

Labor \La"bor\, v. t. [F. labourer, L. laborare.]
   1. To work at; to work; to till; to cultivate by toil.
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            The most excellent lands are lying fallow, or only
            labored by children.                  --W. Tooke.
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   2. To form or fabricate with toil, exertion, or care. "To
      labor arms for Troy." --Dryden.
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   3. To prosecute, or perfect, with effort; to urge
      strenuously; as, to labor a point or argument.
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   4. To belabor; to beat. [Obs.] --Dryden.
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The Collaborative International Dictionary of English v.0.48:

Labor \La"bor\, v. i. [imp. & p. p. Labored; p. pr. & vb. n.
   Laboring.] [OE. labouren, F. labourer, L. laborare. See
   Labor, n.] [Written also labour.]
   1. To exert muscular strength; to exert one's strength with
      painful effort, particularly in servile occupations; to
      work; to toil.
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            Adam, well may we labor still to dress
            This garden.                          --Milton.
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   2. To exert one's powers of mind in the prosecution of any
      design; to strive; to take pains.
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   3. To be oppressed with difficulties or disease; to do one's
      work under conditions which make it especially hard,
      wearisome; to move slowly, as against opposition, or under
      a burden; to be burdened; -- often with under, and
      formerly with of.
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            The stone that labors up the hill.    --Granville.
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            The line too labors, and the words move slow.
                                                  --Pope.
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            To cure the disorder under which he labored. --Sir
                                                  W. Scott.
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            Come unto me, all ye that labor and are heavy laden,
            and I will give you rest.             --Matt. xi. 28
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   4. To be in travail; to suffer the pangs of childbirth; to be
      in labor.
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   5. (Naut.) To pitch or roll heavily, as a ship in a turbulent
      sea. --Totten.
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The Devil's Dictionary (1881-1906):

LABOR, n.  One of the processes by which A acquires property for B.