Source : Webster's Revised Unabridged Dictionary (1913)

Magistral \Mag"is*tral\, a. [L. magistralis: cf. F. magistral.
   See {Magistrate}.]
   1. Pertaining to a master; magisterial; authoritative;
      dogmatic.

   2. Commanded or prescribed by a magister, esp. by a doctor;
      hence, effectual; sovereign; as, a magistral sirup. ``Some
      magistral opiate.'' --Bacon.

   3. (Pharmacy) Formulated extemporaneously, or for a special
      case; -- opposed to {officinal}, and said of prescriptions
      and medicines. --Dunglison.

   {Magistral line} (Fort.), the guiding line, or outline, or
      outline, by which the form of the work is determined. It
      is usually the crest line of the parapet in fieldworks, or
      the top line of the escarp in permanent fortifications.