| Filed Under: Language Leave a Comment. Equestrian is a word used to describe a competitive horseback rider and entered English in 1656 as meaning a “knight on horseback.”. The horse has evolved over fifty million years to become the majestic animal exhibited at various competitions today.Equestrian is from the Latin word for horse, which is equus. Filed Under: Language Leave a Comment. Equestrian is a word used to describe a competitive horseback rider and entered English in 1656 as meaning a “knight on horseback.”. The horse has evolved over fifty million years to become the majestic animal exhibited at various competitions today.