Webster’s Revised Unabridged Dictionary · 1913
Vigor
Vig′or (vĭg′ẽr), n. [OE. vigour, vigor, OF. vigor, vigur, vigour, F. vigueur, fr. L. vigor, fr. vigere to be lively or strong. See Vegetable, Vigil.] 1. Active strength or force of body or mind; capacity for exertion, physically, intellectually, or morally; force; energy.
The vigor of this arm was never vain. Dryden.
2. Strength or force in animal or force in animal or vegetable nature or action; as, a plant grows with vigor.
3. Strength; efficacy; potency.
But in the fruithful earth . . . His beams, unactive else, their vigor find. Milton.
☞ Vigor and its derivatives commonly imply active strength, or the power of action and exertion, in distinction from passive strength, or strength to endure.
Vig′or, v. t. To invigorate. [Obs.] Feltham.