The Collaborative International Dictionary of English v.0.48:

orb weaver \orb" weav`er\, orb-weaver \orb"-weav`er\, n.
   Any spider of the family Araneidae (called also
   Argiopidae) that spins a web with a pattern of lines
   spiraling outward from the center. They have eight similar
   eyes. The golden orb weaver, Mephila clavipes, is known for
   the remarkable dragline silk it produces for use as a frame
   for its web and as a line on which it can plummet down and
   nab prey. This silk has a high tensile strength and is
   stronger than the toughest current synthetic polymer
   (Kevlar).
   [PJC]

WordNet (r) 3.0 (2006):

orb-weaver
    n 1: spiders that spin orb webs; cosmopolitan in distribution
         [syn: Argiopidae, family Argiopidae, orb-weaver]