Nai
Nai (นาย) – one step up from Phrai plain commoner – is the most junior of the ranks, and not normally considered noble. Nowadays used as an equivalent for Mister, with Nang Sao (นางสาว) the equivalent of Miss and Nang (นาง) the equivalent of Mrs. or Ms. Related terms: Chao Nai (เจ้านาย) either royalty or boss; Moon Nai or Chao Khun Moon Nai (มูลนาย หรือเจ้าขุนมูลนาย) master (of Phrai Som.)
Read more about this topic: Thai Royal And Noble Titles, Feudal Lifetime Titles For Male Commoners (all Obsolete)