Source : Webster's Revised Unabridged Dictionary (1913)

Meliorate \Mel"io*rate\ (m[=e]l"y[-o]*r[=a]t), v. t. [imp. & p.
   p. {Meliorated} (-r[=a]`t[e^]d); p. pr. & vb. n.
   {Meliorating}.] [L. melioratus, p. p. of meliorare to
   meliorate, fr. melior better; akin to Gr. ma^llon rather,
   ma`la very. Cf. {Ameliorate}.]
   To make better; to improve; to ameliorate; to soften; to make
   more tolerable.

         Nature by art we nobly meliorate.        --Denham.

         The pure and bening light of revelation has had a
         meliorating influence on mankind.        --Washington.

Meliorate \Mel"io*rate\, v. i.
   To grow better.

Source : WordNet®

meliorate
     v 1: to make better; "The editor improved the manuscript with his
          changes" [syn: {better}, {improve}, {amend}, {ameliorate}]
          [ant: {worsen}]
     2: get better; "The weather improved toward evening" [syn: {better},
         {improve}, {ameliorate}] [ant: {worsen}]