"Hollow foot" is a rarely used term that refers to a characteristic in certain animals, particularly horses, where there is a hollow or concave area in their foot structure. This condition can result in various problems and lameness issues for the affected animals. While "hollow foot" may not have any commonly used synonyms, there are alternative phrases that can be used to describe similar conditions in horses, such as "flat sole", "concave hoof" or "sunken foot". These phrases help convey the same meaning in a more comprehensible way for those unfamiliar with the terminology associated with equine foot health.