eyespot

from WordNet (r) 3.0 (2006)

eyespot
    n 1: an eyelike marking (as on the wings of some butterflies);
         usually a spot of color inside a ring of another color
         [syn: {eyespot}, {ocellus}]

from The Collaborative International Dictionary of English v.0.48

Eye-spot \Eye"-spot`\, n. (Zo["o]l.)
   (a) A simple visual organ found in many invertebrates,
       consisting of pigment cells covering a sensory nerve
       termination.
   (b) An eyelike spot of color.
       [1913 Webster]