ocean -
a large body of water constituting a principal part of the hydrosphere
body of water,
water the part of the earth's surface covered with water (such as a river or lake or ocean); "they invaded our territorial waters"; "they were sitting by the water's edge"
hydrosphere the watery layer of the earth's surface; includes water vapor
deep literary term for an ocean; "denizens of the deep"
ocean -
anything apparently limitless in quantity or volume