Source : Webster's Revised Unabridged Dictionary (1913)

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.

Heft \Heft\, n.
   Same as {Haft}, n. [Obs.] --Waller.

Heft \Heft\, n. [From {Heave}: cf. hefe weight. Cf. {Haft}.]
   1. The act or effort of heaving? violent strain or exertion.
      [Obs.]

            He craks his gorge, his sides, With violent hefts.
                                                  --Shak.

   2. Weight; ponderousness. [Colloq.]

            A man of his age and heft.            --T. Hughes.

   3. The greater part or bulk of anything; as, the heft of the
      crop was spoiled. [Colloq. U. S.] --J. Pickering.

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

            Inflamed with wrath, his raging blade he heft.
                                                  --Spenser.

   2. To prove or try the weight of by raising. [Colloq.]

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

            Inflamed with wrath, his raging blade he heft.
                                                  --Spenser.

   2. To prove or try the weight of by raising. [Colloq.]

Source : WordNet®

heft
     n : the property of being large in mass [syn: {heftiness}, {massiveness},
          {ponderousness}, {ponderosity}]

heft
     v 1: lift or elevate [syn: {heave}, {heave up}, {heft up}]
     2: test the weight of something by lifting it