W meaning in Medical ?

Warmbloods are a group of middle-weight horse types and breeds primarily originating in Europe and registered with organizations that are characterized by open studbook policy, studbook selection, and the aim of breeding for equestrian sport. The term distinguishes these horses from both heavy draft horses ("cold bloods") and refined light saddle horses such as the Thoroughbred, Arabian, and Akhal-Teke ("hot bloods"). Although modern warmbloods are descended from heavier agricultural types systematically upgraded by hotblood influence, the term does not imply that warmbloods are direct crosses of "cold" and "hot".