supertanker

from WordNet (r) 3.0 (2006)

supertanker
    n 1: the largest class of oil tankers

from The Collaborative International Dictionary of English v.0.48

Tank ship \Tank ship\, Tank vessel \Tank vessel\ . (Naut.)
   A vessel fitted with tanks for the carrying of oil or other
   liquid in bulk; -- called also {tanker}. A tank ship of very
   large capacity is called a {supertanker}.
   [Webster 1913 Suppl. +PJC]