inframedian

from The Century Dictionary.

• In zoögeog., below the median belt or zone: applied to one of five zones into which the sea-bottom has been divided with reference to its fauna. The inframedian is succeeded by the abyssal zone. See zone.

from the GNU version of the Collaborative International Dictionary of English.

• adjective (Zoölogical Geog.) Of or pertaining to the interval or zone along the sea bottom, at the depth of between fifty and one hundred fathoms.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective Of or relating to the interval or zone along the sea bottom, at the depth of between fifty and one hundred fathoms.