Efficient, a.
Etymology: [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. The efficient cause is the working cause. Wilson.
Syn. -- Effective; effectual; competent; able; capable; material; potent.
1 other Webster entry under this spelling
Efficient, n.
An efficient cause; a prime mover. God . . . moveth mere natural agents as an efficient only. Hooker.
Shades of meaning
Fernald lists efficient only as an antonym, under vain.
He lists it without comment; the entries above explain its neighbors.
Synonyms
none given