without light; specif., pertaining to that part () of the ocean below a depth of c. 100 m (c. 328 ft) which does not receive sufficient sunlight for photosynthesis
See aphotic in American Heritage Dictionary 4
(ā-fōˈtĭk)
adjective
Having no light.
Of or relating to the region of a body of water that is not reached by sunlight and in which photosynthesis is unable to occur.