A palfrey is a type of horse highly valued as a riding horse in the Middle Ages. It is not a breed.
The word "palfrey" is cognate with the German word for horse (of any type), "Pferd". Both descend from Latin "paraveredus", meaning a post horse or courier horse. The German term for a palfrey, meanwhile, is Zelter, which literally means "ambler" and is cognate with the Icelandic tölt.