| Noun | 1. | reference frame - a system that uses coordinates to establish position organization, arrangement, organisation, system - an organized structure for arranging or classifying; "he changed the arrangement of the topics"; "the facts were familiar but it was in the organization of them that he was original"; "he tried to understand their system of classification" Cartesian coordinate system - a coordinate system for which the coordinates of a point are its distances from a set perpendicular lines that intersect at the origin of the system coordinate axis - one of the fixed reference lines of a coordinate system inertial frame, inertial reference frame - a coordinate system in which Newton's first law of motion is valid space-time, space-time continuum - the four-dimensional coordinate system (3 dimensions of space and 1 of time) in which physical events are located |