What term describes a white marking that covers only the area around the horse's fetlock?

The term that accurately describes a white marking covering only the area around a horse's fetlock is "ankle." This designation focuses specifically on the area just above the hoof, which in equine terminology, refers distinctly to the portion around the fetlock joint. A marking in this region would be seen as characteristic of certain breeds or colors, and is identified by its location, hence the use of the term "ankle."

In contrast, the term "pastern" refers to the section of a horse's limb extending from the fetlock joint to the top of the hoof. "Half-stocking" describes markings that extend higher than a fetlock, often reaching partway up the leg. "Coronet" refers to a very specific marking at the top of the hoof, just above the coronary band, and does not include the fetlock area. Thus, the correct understanding of these terms highlights the distinct characteristics that define each marking on a horse's legs.