noun: (anatomy) One of the two prominences at the posterior extremity of the frog of a horse's foot.
noun: (botany) A globular head of flowers.
noun: (geometry) A hypersphere in 4-dimensional Euclidean space defined as the set of all points that are at a given distance from a given point, also called a 3-sphere.
verb: (obsolete) To look gloomy, morose, or sullen.
