Emily Dickinson Lexicon

EF-FI'CIENCE, or EF-FI'CIEN-CY, n. [L. efficiens, from efficio. See Effect.]

1. The set of pricing effects; a causing to be or exist; effectual agency. The manner of this divine efficiency is far above us. Hooker. Gravity does not proceed from the efficiency of any contingent or unstable agent. Woodward.
2. Power of producing the effect intended; active competent power.