Source : Webster's Revised Unabridged Dictionary (1913)

Hemimetabola \Hem`i*me*tab"o*la\, n. pl. [NL. See {Hemi-}, and
   {Metabola}.] (Zo["o]l.)
   Those insects which have an incomplete metamorphosis.

Source : WordNet®

Hemimetabola
     n : subclass of insects characterized by gradual and usually
         incomplete metamorphosis [syn: {Exopterygota}, {subclass
         Exopterygota}]