derived from the Latin word
interrex (one who holds office between the death of a supreme magistrate and the appoint)
derived from the Medieval Latin word
rex (king)
derived from the Latin word
regere (rule, guide; manage)
using the Proto-Indo-European prefix
reg- (to move in a straight line)
using the Latin prefix
inter-derived from the Latin word
inter (between)
derived from the Proto-Indo-European root
*en