rel·a·tiv·i·ty 
(rĕl′ə-tĭvĭ-tē)
(rĕl′ə-tĭvĭ-tē)n.
1. The quality or state of being relative.
2. A state of dependence in which the existence or significance of one entity is solely dependent on that of another.
3. Physics
a. Special relativity.
b. General relativity.