Typically used as part of the compound 優生学 (eugenics) or in related contexts; rarely used as a standalone noun.
See also: 優生学
Eugenics is a field of study that aims at genetic improvement.
eugenics
eugenic thought; idea of eugenics
eugenic sterilization
eugenic marriage
Abbreviation of 優生学 (eugenics), from 優 (superior) and 生 (life/birth).