power, fitness or capacity

ability to perform

the state, quality, of being efficient

adeptness, effectiveness

(of a person) the force, strength, capacity, to do things and get things done

person's spirit and vigor

great effort, power, strength; of may

ability, power

strength (especially of drugs)

effectiveness

(in living things) the ability to do or act; energy that can be used to do work; authority; influence

ability, competence

the quality of being useful; a public service such as the supply of water or a bus service

serviceableness

genuineness, lawfulness

genuineness, lawfulness