(oceanography) That part of the deep body of an ocean or lake that receives insufficient sunlight for photosynthesis to be possible.

The forehead and nose considered together as a region of the face that can, in some people, produce excess sebum compared to other parts of the face.

(geography) The part of the Earth between the geographical South Pole and the Antarctic Circle.

(military) Rear part of a theater of war or theater of operations (behind but contiguous to the combat zone) which contains the lines of communications, establishments for supply and evacuation, and other agencies required for the immediate support and maintenance of the field forces. Also called COMMZ.

The region, between the Tropic of Cancer and the Tropic of Capricorn, characterised by a hot and humid climate; the tropics.

(biology) an environment that allows the development of adaptive radiation

Any large portion of the Earth's land area which has a generally uniform climate and soil and therefore a high degree of uniformity in the composition of species; a number of different classifications have been proposed by different people.

(military) An area into which a designated ground unit or fire support ship delivers, or is prepared to deliver, fire support. Fire may or may not be observed.

(military) A tactical subdivision of a larger area, the responsibility for which is assigned to a tactical unit; generally applied to offensive action.

A neutral area, between hostile forces, designed to prevent hostilities. / (US) A transitional area between areas of different land use.