The Collaborative International Dictionary of English v.0.48:

Ophidion \O*phid"i*on\, n.; pl. Ophidia. [L., fr. Gr. ? little
   snake, fr. 'o`fis a serpent.] (Zool.)
   The typical genus of ophidioid fishes. [Written also
   Ophidium.] See Illust. under Ophidioid.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Ophidia \O*phid"i*a\, prop. n. pl. [NL., fr. Gr. ?, dim. of
   'o`fis a snake.] (Zool.)
   The suborder of reptiles which includes the serpents; called
   also Serpentes.
   [1913 Webster +PJC]

   Note: The most important divisions are: the Solenoglypha,
         having erectile perforated fangs, as the rattlesnake;
         the Proteroglypha, or elapine serpents, having
         permanently erect fang, as the cobra; the Asinea, or
         colubrine serpents, which are destitute of fangs; and
         the Opoterodonta, or Epanodonta, blindworms, in
         which the mouth is not dilatable.
         [1913 Webster]

WordNet (r) 3.0 (2006):

Ophidia
    n 1: snakes [syn: Serpentes, suborder Serpentes, Ophidia,
         suborder Ophidia]