The Collaborative International Dictionary of English v.0.48:

Architeuthis \Ar`chi*teu"this\, n. [NL., fr. Gr. pref. ? + ?, ?,
   a kind of squid.] (Zool.)
   A genus of gigantic cephalopods, allied to the squids, found
   esp. in the North Atlantic and about New Zealand.
   [1913 Webster]

WordNet (r) 3.0 (2006):

architeuthis
    n 1: largest mollusk known about but never seen (to 60 feet
         long) [syn: architeuthis, giant squid]