Agile, a.
Etymology: [F. agile, L. agilis, fr. agere to move. See Agent.]
Having the faculty of quick motion in the limbs; apt or ready to move; nimble; active; as, an agile boy; an agile tongue. Shaking it with agile hand. Cowper.
Syn. -- Active; alert; nimble; brisk; lively; quick.
Shades of meaning
Fernald has no entry of its own for agile; he lists it under active, nimble.
Where he writes about it:
Active refers to both quickness and constancy of action; in the former sense it is allied with agile, alert, brisk, etc.; in the latter, with busy, diligent, industrious. — from active