Competence, Competency, n.
Etymology: [Cf. F. compétence, from L. competentia agreement.]
1. The state of being competent; fitness; ability; adequacy; power. The loan demonstrates, in regard to instrumental resources, the competency of this kingdom to the assertion of the common cause. Burke. To make them act zealously is not in the competence of law. Burke.
2. Property or means sufficient for the necessaries and conveniences of life; sifficiency without excess. Reason's whole pleasure, all the joys of sense, Lie in three words -- health, peace, and competence. Pope. Superfluity comes sooner by white hairs, but competency lives longer. Shak.
3. (Law) (a) Legal capacity or qualifications; fitness; as, the competency of a witness or of a evidence. (b) Right or authority; legal power or capacity to take cognizance of a cause; as, the competence of a judge or court. Kent.
Shades of meaning
Fernald has no entry of its own for competency; he lists it under power.
Where he writes about it:
Competency is equal to the occasion, readiness prompt for the occasion. — from power