The Collaborative International Dictionary of English v.0.48:

Detachment \De*tach"ment\, n. [Cf. F. d['e]tachement.]
   1. The act of detaching or separating, or the state of being
      detached.
      [1913 Webster]

   2. That which is detached; especially, a body of troops or
      part of a fleet sent from the main body on special
      service.
      [1913 Webster]

            Troops . . . widely scattered in little detachments.
                                                  --Bancroft.
      [1913 Webster]

   3. Abstraction from worldly objects; renunciation.
      [1913 Webster]

            A trial which would have demanded of him a most
            heroic faith and the detachment of a saint. --J. H.
                                                  Newman.
      [1913 Webster]

WordNet (r) 3.0 (2006):

detachment
    n 1: avoiding emotional involvement [syn: withdrawal,
         detachment]
    2: the act of releasing from an attachment or connection [syn:
       detachment, disengagement]
    3: the state of being isolated or detached; "the insulation of
       England was preserved by the English Channel" [syn:
       insulation, insularity, insularism, detachment]
    4: a small unit of troops of special composition
    5: coming apart [syn: separation, breakup, detachment]