Caisen is a modern American spelling of Kasen or Cason, a surname-style name of uncertain origin that is usually explained as "son of Cass" or as a respelling built on Casey and Jason. The many spellings, Kasen, Kaysen, Kaison and Caisen, show that it is a name shaped by sound rather than history. Caisen ranked number 6048 in 2015 and has climbed to number 2574 in 2025, its best rank so far.