Caysen is a modern American respelling of Cason or Kasen, a surname-style coinage that pairs the sound of Case or Casey, usually linked to the Irish word for "vigilant", with the fashionable -son ending. It has no fixed meaning of its own and lives on its sound, which sits between Jason and Grayson. Caysen ranked number 6929 in 2000, peaked at number 1157 in 2022 and stands at number 1339 in 2025.