Definition of Nautiloidea in US English:

Nautiloidea

noun

Zoology
  • With plural or singular concord. A subclass of cephalopod molluscs possessing a many-chambered shell (either straight or coiled), of which the genus Nautilus is the only living member; (in some classifications) one of a number of subdivisions of the tetrabranchiate cephalopods.

Origin

Late 19th century; earliest use found in Johnson's New Universal Cyclopedia. From scientific Latin Nautiloidea (attributed to L. Agassiz, 1847) from Nautilus + -oidea.