Lewis & Short

astrăgălus, i, m., = ἀστράγαλος (the ankle-bone).

  1. I. In arch.
    1. A. A little round moulding in the form of a ring, which encircles the upper part of a column, an astragal, Vitr. 3, 3.
    2. B. Lesbius, a sort of moulding carved to represent a string of pearls, a festoon, a stem with seeds of grain or olives, Vitr. 4, 6.
  2. II. A leguminous plant, Spanish tragacanth: Astragalus Baeticus, Linn.; Plin. 26, 8, 29, § 46.