The Collaborative International Dictionary of English v.0.48:

Proportionate \Pro*por"tion*ate\, a. [L. proportionatus. See
   Proportion.]
   Adjusted to something else according to a proportion;
   proportional. --Longfellow.
   [1913 Webster]

         What is proportionate to his transgression. --Locke.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Proportionate \Pro*por"tion*ate\, v. t. [imp. & p. p.
   Proportionated; p. pr. & vb. n. Proportionating.] [Cf.
   Proportion, v.]
   To make proportional; to adjust according to a settled rate,
   or to due comparative relation; to proportion; as, to
   proportionate punishment to crimes.
   [1913 Webster]

WordNet (r) 3.0 (2006):

proportionate
    adj 1: being in due proportion; "proportionate representation of
           a minority group" [ant: disproportional,
           disproportionate]
    2: agreeing in amount, magnitude, or degree
    3: exhibiting equivalence or correspondence among constituents
       of an entity or between different entities [syn:
       harmonious, proportionate, symmetrical]