Tôn Thất [a] [b] (or Tôn Nữ for female [1]) is a two-character Vietnamese compound surname, originating from the Nguyễn dynasty. It is the surname for members of the imperial family that were not direct first-born descendants of the Emperor, and therefore considered collateral relatives of the Nguyễn dynasty. [2]
This surname was originally Tông Thất ( 宗室), which is derived from a Sino-Vietnamese word, meaning "clan members" or " royal family members". [3] The surname was changed to Tôn Thất ( 尊 室) after Thiệu Trị ( né: Nguyễn Phúc Miên Tông) became the emperor due to naming taboo.