Custos-regni Definition

Origin of Custos-regni

• First attested in the plural in October 1644 and in the singular in 1683; Latin: cūstōs (“guard”, “protector”; “guardian”; “keeper”, “custodian”) + rēgnī (“of royal power”; genitive singular of rēgnum, “royal power”, “kingdom”) = “custodian of royal power” ≈ “guardian of the realm”.

  From Wiktionary