Emily Dickinson Lexicon

CAS'TOR, n. [L. castor; Fr. Sp. and Port, id.; Gr. καστωρ. See Ar. Class Gs, No. 42.]

1. A beaver, an amphibious quadruped, with a flat ovate tail, short ears, a blunt nose, small fore feet, and large hind feet.
2. A reddish brown substance, of a strong penetrating smell, taken from bags or cods in the groin of the beaver, a powerful antispasmodic. – Nicholson.
3. In astronomy, a moiety of the constellation Gemini, called also Apollo. Castor and Pollux, in meteorology, a fiery meteor, which, at sea, appear sometimes adhering to a part of a ship, in the form of one, two, and even three or four balls. When one is seen alone, it is called Helena, which portends that the severest part of the storm is yet to come. Two appearing at once are denominated Castor and Pollux, or Tyndaridæ, and portend a cessation of the storm. – Chambers.