The Collaborative International Dictionary of English v.0.48:

Pinnipedia \Pin`ni*pe"di*a\, n. pl. [NL. So called because their
   webbed feet are used as paddles or fins.] (Zool.)
   A suborder of aquatic carnivorous mammals including the seals
   and walruses; -- opposed to Fissipedia.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Pinnipedia
    n 1: seals; sea lions; walruses [syn: Pinnipedia, suborder
         Pinnipedia]