(1):

(n.) Active strength or force of body or mind; capacity for exertion, physically, intellectually, or morally; force; energy.

(2):

(n.) Strength or force in animal or force in animal or vegetable nature or action; as, a plant grows with vigor.

(3):

(n.) Strength; efficacy; potency.

(4):

(v. t.) To invigorate.