rel ‧ a ‧ tiv ‧ i ‧ ty /ˌreləˈtɪvəti, ˌreləˈtɪvɪti/ BrE AmE noun [uncountable]
the relationship in ↑ physics between time, space, and movement according to Einstein’s ↑ theory
rel ‧ a ‧ tiv ‧ i ‧ ty /ˌreləˈtɪvəti, ˌreləˈtɪvɪti/ BrE AmE noun [uncountable]
the relationship in ↑ physics between time, space, and movement according to Einstein’s ↑ theory
Longman Dictionary of Contemporary English. Longman - Словарь современного английского языка. 2012