Source : Webster's Revised Unabridged Dictionary (1913)

Premature \Pre`ma*ture"\, a. [L. praematurus; prae before +
   maturus ripe. See {Mature}.]
   1. Mature or ripe before the proper time; as, the premature
      fruits of a hotbed.

   2. Happening, arriving, existing, or performed before the
      proper or usual time; adopted too soon; too early;
      untimely; as, a premature fall of snow; a premature birth;
      a premature opinion; premature decay.

   3. Arriving or received without due authentication or
      evidence; as, a premature report. -- {Pre`ma*ture"ly},
      adv. -- {Pre`ma*ture"ness}, n.

Source : WordNet®

premature
     adj 1: born after a gestation period of less than the normal time;
            "a premature infant" [ant: {full-term}]
     2: too soon or too hasty; "our condemnation of him was a bit
        previous"; "a premature judgment" [syn: {previous(p)}]
     3: uncommonly early or before the expected time; "illness led
        to his premature death"; "alcohol brought him to an
        untimely end" [syn: {untimely}]