In Physics
Space is one of the few fundamental quantities in physics, meaning that it cannot be defined via other quantities because there is nothing more fundamental known at present. Thus, similar to the definition of other fundamental quantities, space is defined via measurement. Currently, the standard space interval, called a standard meter or simply meter, is defined as the distance traveled by light in a vacuum during a time interval of 1/299792458 of a second. This definition coupled with present definition of time makes our space-time to be Minkowski space and makes special relativity theory to be absolutely correct by definition.
In classical physics, space is a three-dimensional Euclidean space where any position can be described using three coordinates. Special and general relativity uses space-time rather than space; space-time is modeled as a four-dimensional space with the time axis being imaginary in special relativity and real in general relativity, and currently there are many theories which use more than four-dimensional spaces.
Before Einstein's work on relativistic physics, time and space were viewed as independent dimensions. Einstein's discoveries have shown that due to relativity of motion our space and time can be mathematically combined into one symmetric object — space-time.