noun

1. the condition, fact, or quality of being relative
2. the close dependence of one occurrence, value, quality, etc. on another
3. Philos.
   1. relativism
   2. relativity of knowledge
4. Physics 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 motion2) the velocity of light is constant and not dependent on the motion of the source3) no energy can be transmitted at a velocity greater than that of light4) the mass of a body in motion is a function of the energy content and varies with the velocity5) matter and energy are equivalent6) time is relative7) space and time are interdependent and form a four-dimensional continuum8) 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