1. 
2. 
[syn: effective, efficient]
The Collaborative International Dictionary of English v.0.48:
efficient \ef*fi"cient\ ([e^]f*f[i^]sh"ent), a. [L. efficiens,
   -entis, p. pr. of efficere to effect: cf. F. efficient. See
   Effect, n.]
   Causing effects; producing results; that makes the effect to
   be what it is; actively operative; not inactive, slack, or
   incapable; characterized by energetic and useful activity;
   as, an efficient officer, power.
   [1913 Webster]
         The efficient cause is the working cause. --Wilson.
   Syn: Effective; effectual; competent; able; capable;
        material; potent.
        [1913 Webster]
The Collaborative International Dictionary of English v.0.48:
Efficient \Ef*fi"cient\, n.
   An efficient cause; a prime mover.
   [1913 Webster]
         God . . . moveth mere natural agents as an efficient
         only.                                    --Hooker.
   [1913 Webster]
WordNet (r) 3.0 (2006):
efficient
    adj 1: being effective without wasting time or effort or
           expense; "an efficient production manager"; "efficient
           engines save gas" [ant: inefficient]
    2: able to accomplish a purpose; functioning effectively;
       "people who will do nothing unless they get something out of
       it for themselves are often highly effective
       persons..."-G.B.Shaw; "effective personnel"; "an efficient
       secretary"; "the efficient cause of the revolution" [syn:
       effective, efficient]
Moby Thesaurus II by Grady Ward, 1.0:
39 Moby Thesaurus words for "efficient":
   able, active, adequate, au fait, banausic, capable, competent,
   economic, effective, effectual, efficacious, equal to, feasible,
   fit, fitted, fitted for, functional, go, journeyman, operable,
   operational, operative, practicable, practical, pragmatic,
   productive, proficient, qualified, realizable, suited, thrifty,
   unwasteful, up to, up to snuff, well-fitted, well-qualified,
   well-suited, workable, worthy