The Collaborative International Dictionary of English v.0.48:

Honorarium \Hon`o*ra"ri*um\, Honorary \Hon"or*a*ry\, n. [L.
   honorarium (sc. donum), fr. honorarius. See Honorary, a.]
   1. A fee offered to professional men for their services; as,
      an honorarium of one thousand dollars. --S. Longfellow.
      [1913 Webster]

   2. (Law) An honorary payment, usually in recognition of
      services for which it is not usual or not lawful to assign
      a fixed business price. --Heumann.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Honorary \Hon"or*a*ry\, a. [L. honorarius, fr. honor honor: cf.
   F. honoraire.]
   1. Done as a sign or evidence of honor; as, honorary
      services. --Macaulay.
      [1913 Webster]

   2. Conferring honor, or intended merely to confer honor
      without emolument; as, an honorary degree. "Honorary
      arches." --Addison.
      [1913 Webster]

   3. Holding a title or place without rendering service or
      receiving reward; as, an honorary member of a society.
      [1913 Webster]

WordNet (r) 3.0 (2006):

honorary
    adj 1: given as an honor without the normal duties; "an honorary
           degree"