i Register
In some senses, light-horseman is marked as obsolete, US. Watch for register when choosing this word.
noun
A soldier who serves in the light cavalry.
A member of species Chaetodipterus faber of West Indian fish with a high dorsal fin and brilliant colours.
A member of species Pagrus auratus of snapper, whose skull is shaped in the front like a cap worn by light-horsemen.