Lewis & Short

dĕcānus, i, m. [decem].

  1. I. A chief of ten, one set over ten persons (late Lat.).
    1. A. Over soldiers, Veg. Mil. 2, 8.
    2. B. Over monks, a dean, Hier. Ep. 22, no. 35.
    3. C. The chief of the corpse-bearers, Cod. Just. 1, 2, 4; 9.
    4. D. As a judge, Vulg. Exod. 18, 21; Deut. 1, 15.
  2. II. A kind of officer at the imperial court, Cod. 12, 27, 1.
  3. III. In astrology, the chief of ten parts of a zodiacal sign, Firm. Math. 2, 4.