complementarity
1. [ noun ] a relation between two opposite states or principles that together exhaust the possibilities
Related terms: ungradable_opposition
2. [ noun ] the interrelation of reciprocity whereby one thing supplements or depends on the other
Examples:

"the complementarity of the sexes"

Related terms: reciprocality
Similar spelling:   complementary
  complementary_dna
  complemental
  complimentary
  complementation