complementary color

/K AA0 M P L AH0 M EH1 N T R IY0 K AH0 L ER0/
noun
  1. 1

    (colour science) Either of two colours which, when mixed, produce a white or grey.

  2. 2

    A colour which is regarded as the opposite of another, so that the two colours together form a pleasing contrast.

Source: https://en.wiktionary.org/wiki/complementary%20color, https://en.wiktionary.org/wiki/complementary%20colour