1) Having nothing to breathe 2) Hypoxia 3) Lacking oxygen 4) Oxygen-deprived 
Low oxygen.
The lack of oxygen such as the inadequate oxygenation of the blood (anoxia). In aquatic environmental chemistry it refers to water that has become oxygen poor due to the bacterial decay of organic matter.
Lack of oxygen. An adjective usually used to desribe a microbial habitat. ... (09 Oct 1997) ... 
Type: Term Pronunciation: an-ok′sik Definitions: 1. Denoting or characteristic of anoxia.
Anoxic: Pertaining to anoxia, an absence or near absence of oxygen.
describes a condition in which a liquid has become devoid of oxygen and in which certain microorganisms can obtain oxygen from nitrate or nitrite ions
with abnormally low levels of oxygen.
[adj] - relating to or marked by a severe deficiency of oxygen in tissues or organs
anoxia, anoxic Absence or almost complete absence of oxygen from inspired gases, arterial blood, or tissues; to be differentiated from hypoxia.
Lacking oxygen. 
adjective relating to or marked by a severe deficiency of oxygen in tissues or organs
An environment in which there is no free oxygen present. A situation that commonly arises in natural habitats when the biological demand for oxygen exceeds the supply, for example in sediments or when a site is organically polluted.