(aviation) The deployment of an aircraft's landing gear by the use of gravity.

(oil industry) A specific gravity scale measuring the relative density of various petroleum liquids, expressed in degrees.

(physics) A branch of theoretical physics aiming to unite quantum mechanics with general relativity. / (quantum mechanics) The gravitational force modeled as a quantum field.

(physics) Britain and Canada standard spelling of center of gravity.

(science fiction) Any of various concepts, systems or devices that would oppose or cancel out the force of gravity.

(physics) A point, near or within a body, through which its weight can be assumed to act when considering forces on the body and its motion under gravity. This coincides with the center of mass in a uniform gravitational field.

A homemade device used to smoke marijuana, consisting of a plastic jug with the bottom cut out and immersed in a vat of water, which is then raised to create a vacuum beneath its bowl of lit marijuana.

(physics) The ratio of the mass of a substance to that of an equal volume of water at 4°C (or to some other reference substance)

(physics) An instrument that measures the local acceleration due to gravity (strength of the gravitational field).

A katabatic wind.