yin and yang
concept of dualism and complementarity in Chinese philosophy, cosmology, traditional medicine, fengshui, and protoscience, opposing “yang“ (for solar, masculine, active, warm) with “yin“ (for lunar, feminine, passive, cool)
en-US/ˈjɪn ˈænd jɑŋ/
en-GB/ˈjɪn ən ˈjæŋ/