noun
obscenity; lewd conduct; sexual immorality
Refers to indecent or immoral sexual behavior, often used in legal or formal contexts. The gloss 'harlotry' is archaic and not a primary modern meaning.
彼は淫行の罪で逮捕された。
He was arrested on charges of lewd conduct.
その宗教団体は淫行を厳しく禁じている。
That religious group strictly forbids sexual immorality.
Compound of 淫 (いん, 'lewd, obscene') and 行 (こう, 'act, conduct'). The exact historical derivation is uncertain, but the term has been used in formal and legal contexts to denote immoral sexual behavior.