prince regent /ˌpɹɪns ˈɹiːd͡ʒ(ə)nt/ noun1 •A prince who rules a country as a regent in place of a monarch who is unfit to rule for a particular reason.Accord betwixt D. Raymond Berenger, Prince Regent of Arragon, with the Templers and Hospitaliers, vpon the testament of King D. Alphonso. — 1612 formsprince regents · princes regent · princes regents