Pronunciation: (i-kī'nus),[key] —n., —pl.-niPronunciation: (-nī).[key] 1. any sea urchin of the genus Echinus. 2. Archit. a. an ovolo molding, esp. one having an outline with several radii or one carved with an egg-and-dart pattern. See illus. under molding. b. the prominent circular molding supporting the abacus of a Doric or Tuscan capital.
c. Also called cymatium. the circular molding, usually carved with an egg-and-dart pattern, forming part of an Ionic capital between the volutes and under the balteus.