The evolution of the name would have been καισαρ → kaisar → *kēsar → Kíarr → Kiárr. A third possibility is that it originates from contacts with Rome beside the probably early borrowing Rúm in words such as Rúmverjar ("Roman soldiers").
The development of the name would have been affected by a range of cultural and linguistic influences, including interactions with Roman powers and exchange with neighboring cultures.