- Of or concerning the period or zone along the water base, within depth of between fifty plus one hundred fathoms.
- Of or regarding the interval or area across the water bottom, on depth of between fifty plus one hundred fathoms.
- In zoögeog., underneath the median belt or area: placed on one of five zones into that the sea-bottom happens to be divided with reference to its fauna. The inframedian is succeeded because of the abyssal zone. See area.