BENTHOS
benthos
(noun) organisms (plants and animals) that live at or near the bottom of a sea
benthos, benthic division, benthonic zone
(noun) a region including the bottom of the sea and the littoral zones
Source: WordNet® 3.1
Etymology
Noun
benthos (plural not attested)
The flora and fauna at the bottom of a body of water.
Source: Wiktionary
Ben"thos, n. [NL., fr. Gr. depth of the sea.]
Definition: The bottom of the sea, esp. of the deep oceans; hence (Bot. &
Zoöl.), the fauna and flora of the sea bottom; -- opposed to
plankton.
Source: Webster’s Unabridged Dictionary 1913 Edition