either of two theories developed by Albert Einstein, the special theory of relativity, which requires that the laws of physics shall be the same as seen by any two different observers in uniform relative motion, and the general theory of relativity which considers observers with relative acceleration and leads to a theory of gravitation

dependence upon some variable factor such as the psychological, social, or environmental context

the state or quality of being relative

the condition, fact, or quality of being relative

the close dependence of one occurrence, value, quality, etc. on another

the fact, principle, or theory of the relative, rather than absolute, character of motion, velocity, mass, etc., and the interdependence of matter, time, and space: as developed and mathematically formulated by Albert Einstein and H. A. Lorentz in the special (or restricted) theory of relativity and by Einstein in the general theory of relativity (an extension covering the phenomena of gravitation), the theory of relativity includes the statements that: 1) there is no observable absolute motion, only relative motion 2) the velocity of light is constant and not dependent on the motion of the source 3) no energy can be transmitted at a velocity greater than that of light 4) the mass of a body in motion is a function of the energy content and varies with the velocity 5) matter and energy are equivalent 6) time is relative 7) space and time are interdependent and form a four-dimensional continuum 8) the presence of matter results in a “warping” of the space-time continuum, so that a body in motion passing nearby will describe a curve, this being the effect known as gravitation, as evidenced by the deflection of light rays passing through a gravitational field