The Collaborative International Dictionary of English v.0.48:

part-time \part-time\ adv.
   For less than the usual full time appropriate to an activity;
   on a part-time basis; as, to sell real estate part-time.
   Opposed to full-time.
   [WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

part-time \part-time\ n.
   A working schedule occupying less than full time, i.e. less
   than 35 hours per week.

   Syn: part time.
        [WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

part-time \part-time\ adj.
   1. Occupying less than the entire time appropriate to an
      activity; as, a part-time job. Opposed to full-time.
      [WordNet 1.5]

   2. Employed for less than the full time usually expended at a
      task or occupation; as, part-time employees; a part-time
      teacher. Opposed to full-time. Commonly, thirty-five
      hours per week or more is considered full-time, and less
      than 30 is part-time work.
      [PJC]

WordNet (r) 3.0 (2006):

parttime
    adj 1: involving less than the standard or customary time for an
           activity; "part-time employees"; "a part-time job" [syn:
           part-time, parttime] [ant: full-time]