Marrying another person, knowing that one or both are already married is termed?

The term for marrying another person while one or both parties are already married is bigamy. Bigamy is a legal offense in which an individual enters into a marriage with someone despite being married to someone else at the same time. This practice is considered illegal and is punishable under the law because it undermines the legal and social acknowledging of marriage.

In contrast, sodomy typically refers to specific sexual acts, often associated with non-procreative sexual intercourse, and does not pertain to marriage. Adultery, while it involves a marital relationship and can occur when one partner in a marriage engages in sexual relations with someone outside of that marriage, does not involve the act of marrying another person. Therefore, bigamy correctly identifies the act described in the question, making it the appropriate term.