Hypergamy

Esther is crowned in this 1860 woodcut by Julius Schnorr von Karolsfeld.

Hypergamy (colloquially referred to as "dating up" or "marrying up") is a term used in social science for the act or practice of a person dating or marrying a spouse perceived to be of higher "mating value" than themselves.

The antonym "hypogamy" refers to the inverse: marrying a person perceived to be of lower "mating value" (colloquially "marrying down"). The term hypergyny can also be used to describe the practice of women marrying up. Concepts such as hypergamy, hypogamy, and hypergyny could be considered special cases of mésalliance.