The Collaborative International Dictionary of English v.0.48:

Grasp \Grasp\, v. t. [imp. & p. p. Grasper; p. pr. & vb. n.
   Qraspine.] [OE. graspen; prob. akin to LG. grupsen, or to
   E. grope. Cf. Grab, Grope.]
   1. To seize and hold by clasping or embracing with the
      fingers or arms; to catch to take possession of.
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            Thy hand is made to grasp a palmer's staff. --Shak.
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   2. To lay hold of with the mind; to become thoroughly
      acquainted or conversant with; to comprehend.
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The Collaborative International Dictionary of English v.0.48:

Grasp \Grasp\, v. i.
   To effect a grasp; to make the motion of grasping; to clutch;
   to struggle; to strive.
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         As one that grasped And tugged for life and was by
         strength subdued.                        --Shak.
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   To grasp at, to catch at; to try to seize; as, Alexander
      grasped at universal empire,
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The Collaborative International Dictionary of English v.0.48:

Grasp \Grasp\, n.
   1. A gripe or seizure of the hand; a seizure by embrace, or
      infolding in the arms. "The grasps of love." --Shak.
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   2. Reach of the arms; hence, the power of seizing and
      holding; as, it was beyond his grasp.
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   3. Forcible possession; hold.
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            The whole space that's in the tyrant's grasp.
                                                  --Shak.
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   4. Wide-reaching power of intellect to comprehend subjects
      and hold them under survey.
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            The foremost minds of the next . . . era were not,
            in power of grasp, equal to their predecessors. --Z.
                                                  Taylor.
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   5. The handle of a sword or of an oar.
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WordNet (r) 3.0 (2006):

grasp
    n 1: understanding of the nature or meaning or quality or
         magnitude of something; "he has a good grasp of accounting
         practices" [syn: appreciation, grasp, hold]
    2: the limit of capability; "within the compass of education"
       [syn: compass, range, reach, grasp]
    3: an intellectual hold or understanding; "a good grip on French
       history"; "they kept a firm grip on the two top priorities";
       "he was in the grip of a powerful emotion"; "a terrible power
       had her in its grasp" [syn: grip, grasp]
    4: the act of grasping; "he released his clasp on my arm"; "he
       has a strong grip for an old man"; "she kept a firm hold on
       the railing" [syn: clasp, clench, clutch, clutches,
       grasp, grip, hold]
    v 1: hold firmly [syn: grasp, hold on]
    2: get the meaning of something; "Do you comprehend the meaning
       of this letter?" [syn: grok, get the picture,
       comprehend, savvy, dig, grasp, compass,
       apprehend]