Source : Webster's Revised Unabridged Dictionary (1913)

Inchworm \Inch"worm`\, n. (Zo["o]l.)
   The larva of any geometrid moth. See {Geometrid}.

Source : WordNet®

inchworm
     n : small hairless caterpillar having legs on only its front and
         rear segments; mostly larvae of moths of the family
         Geometridae [syn: {measuring worm}, {looper}]