NOUN (2)

1. any of the minor woodland deities who were companions of Dionysus (similar to the satyrs);

2. the chief satyr in the service of Bacchus; father of Dionysus; usually depicted as drunk and jolly and riding a donkey;

The Collaborative International Dictionary of English v.0.48:

Silenus \Si*le"nus\, n. [L. Silenus the tutor and attendant of
   Bacchus.] (Zool.)
   See Wanderoo.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Wanderoo \Wan`der*oo"\, n. [Cingalese wanderu a monkey.] (Zool.)
   A large monkey (Macacus silenus) native of Malabar. It is
   black, or nearly so, but has a long white or gray beard
   encircling the face. Called also maha, silenus,
   neelbhunder, lion-tailed baboon, and great wanderoo.
   [Written also ouanderoo.]
   [1913 Webster]

   Note: The name is sometimes applied also to other allied
         species.
         [1913 Webster]

WordNet (r) 3.0 (2006):

silenus
    n 1: any of the minor woodland deities who were companions of
         Dionysus (similar to the satyrs)
    2: the chief satyr in the service of Bacchus; father of
       Dionysus; usually depicted as drunk and jolly and riding a
       donkey