The Collaborative International Dictionary of English v.0.48:

Heft \Heft\, v. t. [imp. & p. p. Hefted (Heft, obs.); p. pr.
   & vb. n. Hefting.]
   1. To heave up; to raise aloft.
      [1913 Webster]

            Inflamed with wrath, his raging blade he heft.
                                                  --Spenser.
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   2. To prove or try the weight of by raising. [Colloq.]
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The Collaborative International Dictionary of English v.0.48:

Heft \Heft\, n.
   Same as Haft, n. [Obs.] --Waller.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Heft \Heft\, n. [From Heave: cf. hefe weight. Cf. Haft.]
   1. The act or effort of heaving; violent strain or exertion.
      [Obs.]
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            He craks his gorge, his sides,
            With violent hefts.                   --Shak.
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   2. Weight; ponderousness. [Colloq.]
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            A man of his age and heft.            --T. Hughes.
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   3. The greater part or bulk of anything; as, the heft of the
      crop was spoiled. [Colloq. U. S.] --J. Pickering.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Heft \Heft\, n.; G. pl. Hefte. [G.]
   A number of sheets of paper fastened together, as for a
   notebook; also, a part of a serial publication.

         The size of "hefts" will depend on the material
         requiring attention, and the annual volume is to cost
         about 15 marks.                          --The Nation.
   [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

heft
    n 1: the property of being large in mass [syn: heft,
         heftiness, massiveness, ponderousness, ponderosity]
    v 1: lift or elevate [syn: heave, heave up, heft, heft
         up]
    2: test the weight of something by lifting it