(anatomy) The part of the retina, lacking blood vessels, that is the centre of the macula

(aviation) The top of the Earth's atmosphere, from 50,000 ft (the start of the stratosphere) and up (to the edge of the exosphere at 1000 mi); where the effects of exposure to the environment on human life is similar to that of exposure to space; it being physiologically incompatible with human life.

(botany) That part of a leaf and petiole that grows from an apical meristem.

(botany) That part of a leaf and petiole that grows from a basal meristem.

(Buteo albonotatus), a medium-sized hawk of warm, dry parts of the Americas

plural of zone-tailed hawk

(rare) A massage technique in which heated stones and herbal balls are applied to the feet and lower leg using specific finger and hand techniques, as well as movement manipulation.

The zone near the equator where mixing occurs between the two tropical zones of the atmosphere.

(astrobiology, astronomy) the restricted zone around a sun where the ever shifting habitable zone is always present throughout the main sequence lifetime of that star.

(astrobiology, astronomy) the zone in a disk galaxy lying within the disk which is neither too far from the core so as to be lacking in heavier elements, nor too close to the core as to experience excessive exposures to supernovae, where intelligent life may develop