คุณนาย

From คุณ (kun, “honorific”) +‎ นาย (naai, “chief; lord; master”).

คุณนาย • (kun-naai)

1. a polite term of address to the wife of a public officer holding a royal letter of appointment known as สัญญาบัตร, when the wife is without noble rank or title.
2. a polite term of address to a woman, especially one married or of rank or authority.
3. (often derogatory or sarcastic) woman of high social position or economic class.

• The second sense is often translated as or compared to madam or mistress in English.
• The second sense can be deemed impolite or offensive if used to address an unmarried woman.