NOUN (1)

1. a means to an end; not necessarily a principled or ethical one;


ADJECTIVE (2)

1. serving to promote your interest;
- Example: "was merciful only when mercy was expedient"

2. appropriate to a purpose; practical;
- Example: "in the circumstances it was expedient to express loyalty"

The Collaborative International Dictionary of English v.0.48:

Expedient \Ex*pe"di*ent\a. [L. expediens, -entis, p. pr. of
   expedire to be expedient, release, extricate: cf. F.
   exp['e]dient. See Expedite.]
   1. Hastening or forward; hence, tending to further or promote
      a proposed object; fit or proper under the circumstances;
      conducive to self-interest; desirable; advisable;
      advantageous; -- sometimes contradistinguished from
      right or principled.
      [1913 Webster]

            It is expedient for you that I go away. --John xvi.
                                                  7.
      [1913 Webster]

            Nothing but the right can ever be expedient, since
            that can never be true expediency which would
            sacrifice a greater good to a less.   --Whately.
      [1913 Webster]

   2. Quick; expeditious. [Obs.]
      [1913 Webster]

            His marches are expedient to this town. --Shak.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Expedient \Ex*pe"di*ent\, n.
   1. That which serves to promote or advance; suitable means to
      accomplish an end.
      [1913 Webster]

            What sure expedient than shall Juno find,
            To calm her fears and ease her boding mind?
                                                  --Philips.
      [1913 Webster]

   2. Means devised in an exigency; shift.

   Syn: Shift; contrivance; resource; substitute.
        [1913 Webster]

WordNet (r) 3.0 (2006):

expedient
    adj 1: serving to promote your interest; "was merciful only when
           mercy was expedient" [ant: inexpedient]
    2: appropriate to a purpose; practical; "in the circumstances it
       was expedient to express loyalty"
    n 1: a means to an end; not necessarily a principled or ethical
         one