Late Middle English; earliest use found in John Capgrave (1393–1464), prior of Bishop's Lynn, theologian, and historian. From reign + -er. Compare Middle French regner, regneur.
Definition of reigner in US English:
reigner
nounˈreɪnə
rare
A person who reigns as monarch; a ruler.
Origin
Late Middle English; earliest use found in John Capgrave (1393–1464), prior of Bishop's Lynn, theologian, and historian. From reign + -er. Compare Middle French regner, regneur.