The Collaborative International Dictionary of English v.0.48:

Harvest \Har"vest\ (h[aum]r"v[e^]st), n. [OE. harvest, hervest,
   AS. h[ae]rfest autumn; akin to LG. harfst, D. herfst, OHG.
   herbist, G. herbst, and prob. to L. carpere to pluck, Gr.
   karpo`s fruit. Cf. Carpet.]
   1. The gathering of a crop of any kind; the ingathering of
      the crops; also, the season of gathering grain and fruits,
      late summer or early autumn.
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            Seedtime and harvest . . . shall not cease. --Gen.
                                                  viii. 22.
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            At harvest, when corn is ripe.        --Tyndale.
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   2. That which is reaped or ready to be reaped or gathered; a
      crop, as of grain (wheat, maize, etc.), or fruit.
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            Put ye in the sickle, for the harvest is ripe.
                                                  --Joel iii.
                                                  13.
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            To glean the broken ears after the man
            That the main harvest reaps.          --Shak.
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   3. The product or result of any exertion or labor; gain;
      reward.
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            The pope's principal harvest was in the jubilee.
                                                  --Fuller.
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            The harvest of a quiet eye.           --Wordsworth.
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   Harvest fish (Zool.), a marine fish of the Southern United
      States (Stromateus alepidotus); -- called whiting in
      Virginia. Also applied to the dollar fish.

   Harvest fly (Zool.), an hemipterous insect of the genus
      Cicada, often called locust. See Cicada.

   Harvest lord, the head reaper at a harvest. [Obs.]
      --Tusser.

   Harvest mite (Zool.), a minute European mite (Leptus
      autumnalis), of a bright crimson color, which is
      troublesome by penetrating the skin of man and domestic
      animals; -- called also harvest louse, and harvest
      bug.

   Harvest moon, the moon near the full at the time of harvest
      in England, or about the autumnal equinox, when, by reason
      of the small angle that is made by the moon's orbit with
      the horizon, it rises nearly at the same hour for several
      days.

   Harvest mouse (Zool.), a very small European field mouse
      (Mus minutus). It builds a globular nest on the stems of
      wheat and other plants.

   Harvest queen, an image representing Ceres, formerly
      carried about on the last day of harvest. --Milton.

   Harvest spider. (Zool.) See Daddy longlegs.
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WordNet (r) 3.0 (2006):

harvest mouse
    n 1: any of several small greyish New World mice inhabiting e.g.
         grain fields [syn: American harvest mouse, harvest
         mouse]
    2: small reddish-brown Eurasian mouse inhabiting e.g. cornfields
       [syn: harvest mouse, Micromyx minutus]