Mauretania Caesariensis UK /ˌmɔːɹɪˈteɪnɪə sɪˌzɑːɹɪˈɛnsɪs/US /ˌmɔɹɪˈteɪniə siˌzɑɹiˈɛnzɪs/ noun1 •A province of the Roman Empire, established in AD 42, occupying territory in northwestern Africa roughly corresponding to present-day northern Algeria, with its capital at Caesarēa.