1) Benthic 2) Benthonic 3) Biogeographical region 1) Benthic 2) Benthonic 
• (a.) Relating to the deepest zone or region of the ocean.
Ben'thal adjective [ Greek ... the depth of the sea.] Relating to the deepest zone or region of the ocean. 
benthal 1. Of or pertaining to ocean-depths exceeding 1 000 fathoms or happening on the bottom under a body of water. 2. Relating to the deepest zone or region of the ocean.