The Collaborative International Dictionary of English v.0.48:

Amplify \Am"pli*fy\, v. i.
   1. To become larger. [Obs.]
      [1913 Webster]

            Strait was the way at first, withouten light,
            But further in did further amplify.   --Fairfax.
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   2. To speak largely or copiously; to be diffuse in argument
      or description; to dilate; to expatiate; -- often with on
      or upon. --Watts.
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            He must often enlarge and amplify upon the subject
            he handles.                           --South.
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The Collaborative International Dictionary of English v.0.48:

Amplify \Am"pli*fy\, v. t. [imp. & p. p. Amplified; p. pr. &
   vb. n. Amplifying.] [F. amplifier, L. amplificare. See
   Ample, -fy.]
   1. To render larger, more extended, or more intense, and the
      like; -- used especially of telescopes, microscopes, etc.
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   2. (Rhet.) To enlarge by addition or discussion; to treat
      copiously by adding particulars, illustrations, etc.; to
      expand; to make much of.
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            Troilus and Cressida was written by a Lombard
            author, but much amplified by our English
            translator.                           --Dryden.
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WordNet (r) 3.0 (2006):

amplify
    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: exaggerate or make bigger; "The charges were inflated" [syn:
       inflate, blow up, expand, amplify]
    4: increase the volume of; "amplify sound"