Select the most appropriate one-word substitution for the given group of words. 

An action of marrying a person of a superior caste or class.

Hypergamy

The most appropriate one-word substitution for an action of marrying a person of a superior caste or class is hypergamy.

• Polygamy is the practice of having multiple spouses at the same time.
• Polyandry is the practice of having multiple husbands at the same time.
• Bigamy is the practice of marrying someone while still legally married to someone else.

The word hypergamy is derived from the Greek words hyper, meaning "above", and gamos, meaning "marriage". It is the act of marrying someone of a higher social status or caste. Hypergamy is often practiced in societies where there is a strong emphasis on social hierarchy.