Nudibranchiata

1. n. pl. A division of opisthobranchiate mollusks, having no shell except while very young. The gills are naked and situated upon the back or sides. See Ceratobranchia.

The word meanings were obtained from OPTED(The Online Plain Text English Dictionary), which is based on “The Project Gutenberg Etext of Webster’s Unabridged Dictionary” which is in turn based on the 1913 US Webster’s Unabridged Dictionary (See Project Gutenburg), as a text file.