The Collaborative International Dictionary of English v.0.48:

Minify \Min"i*fy\, v. t. [imp. & p. p. Minified; p. pr. & vb.
   n. Minifying.] [L. minor less + -fly.]
   [1913 Webster]
   1. To make small, or smaller; to diminish the apparent
      dimensions of; to lessen.
      [1913 Webster]

   2. To degrade by speech or action.
      [1913 Webster]

WordNet (r) 3.0 (2006):

minify
    v 1: make smaller; "He decreased his staff" [syn: decrease,
         lessen, minify] [ant: increase]