The Collaborative International Dictionary of English v.0.48:

Magnify \Mag"ni*fy\, v. t. [imp. & p. p. Magnified; p. pr. &
   vb. n. Magnifying.] [OE. magnifien, F. magnifier, L.
   magnificare. See Magnific.]
   1. To make great, or greater; to increase the dimensions of;
      to amplify; to enlarge, either in fact or in appearance;
      as, the microscope magnifies the object by a thousand
      diameters.
      [1913 Webster]

            The least error in a small quantity . . . will in a
            great one . . . be proportionately magnified.
                                                  --Grew.
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   2. To increase the importance of; to augment the esteem or
      respect in which one is held.
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            On that day the Lord magnified Joshua in the sight
            of all Israel.                        --Joshua iv.
                                                  14.
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   3. To praise highly; to laud; to extol. [Archaic]
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            O, magnify the Lord with me, and let us exalt his
            name together.                        --Ps. xxxiv.
                                                  3.
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   4. To exaggerate; as, to magnify a loss or a difficulty.
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   To magnify one's self (Script.), to exhibit pride and
      haughtiness; to boast.

   To magnify one's self against (Script.), to oppose with
      pride.
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The Collaborative International Dictionary of English v.0.48:

Magnify \Mag"ni*fy\, v. i.
   1. To have the power of causing objects to appear larger than
      they really are; to increase the apparent dimensions of
      objects; as, some lenses magnify but little.
      [1913 Webster]

   2. To have effect; to be of importance or significance. [Cant
      & Obs.] --Spectator.
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WordNet (r) 3.0 (2006):

magnify
    v 1: increase in size, volume or significance; "Her terror was
         magnified in her mind" [syn: magnify, amplify]
    2: to enlarge beyond bounds or the truth; "tended to romanticize
       and exaggerate this `gracious Old South' imagery" [syn:
       overstate, exaggerate, overdraw, hyperbolize,
       hyperbolise, magnify, amplify] [ant: downplay,
       minimise, minimize, understate]
    3: make large; "blow up an image" [syn: blow up, enlarge,
       magnify] [ant: reduce, scale down]