The Collaborative International Dictionary of English v.0.48:

dysfunctional \dysfunctional\ adj.
   1. impaired in function; especially of a bodily system or
      organ.
      [WordNet 1.5]

   2. (Psychol.) failing to serve an adjustive purpose; -- of a
      trait or condition; as, dysfunctional behavior.

   Syn: nonadaptive.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

dysfunctional
    adj 1: impaired in function; especially of a bodily system or
           organ
    2: (of a trait or condition) failing to serve an adjustive
       purpose; "dysfunctional behavior" [syn: dysfunctional,
       nonadaptive]