(physics, chemistry) A method of determining the structure of a molecule by assuming that electrons are not fixed to bonds between individual atoms

(astronomy) The sidereal year of a planet. (I.e., in the definition for "sidereal year", replace "Earth" by the given planet.)

(science fiction) A satellite or space station, found in many different works of science fiction, meant to defend a planet against attack from space.

(of a black hole) Synonym of photon sphere

(ophthalmology, neurology) A collection of cranial nerve deficits associated with a mass lesion near the apex of the orbit, often leading to ophthalmoplegia.

(anatomy) One of two openings transmitting nerves and blood vessels to or from the orbit, situated superiorly between the greater wing and the lesser wing of the sphenoid bone.

(anatomy) One of two openings transmitting nerves and blood vessels to or from the orbit, situated inferiorly between the greater wing of the sphenoid bone and the maxilla.

(astrodynamics) A nearly polar orbit in which a satellite passes over the surface of a planet maintaining the same local mean solar time.

(informal, often humorous) The referent of it is dangerous or undesirable and should be eliminated.

A satellite orbit around the Earth within the altitude range of 200 - 2000 km, in which a satellite can communicate with Earth with a small time lag and energy consumption. Abbreviation: LEO.