quality - an essential and distinguishing attribute of something or someone; "the quality of mercy is not strained"--Shakespeare

potency, effectiveness, strength - capacity to produce strong physiological or chemical effects; "the toxin's potency"; "the strength of the drinks"

valence, valency - (chemistry) a property of atoms or radicals; their combining power given in terms of the number of hydrogen atoms (or the equivalent)

valence, valency - (biology) a relative capacity to unite or react or interact as with antigens or a biological substrate

preponderance - superiority in power or influence; "the preponderance of good over evil"; "the preponderance of wealth and power"

puissance - power to influence or coerce; "the puissance of the labor vote"

persuasiveness, strength - the power to induce the taking of a course of action or the embracing of a point of view by means of argument or entreaty; "the strength of his argument settled the matter"

irresistibility, irresistibleness - the quality of being overpowering and impossible to resist

interestingness, interest - the power of attracting or holding one's interest (because it is unusual or exciting etc.); "they said nothing of great interest"; "primary colors can add interest to a room"

chokehold, stranglehold, throttlehold - complete power over a person or situation; "corporations have a strangelhold on the media"; "the president applied a chokehold to labor disputes that inconvenienced the public"

sway - controlling influence

influence - a power to affect persons or events especially power based on prestige etc; "used her parents' influence to get the job"

repellant, repellent - the power to repel; "she knew many repellents to his advances"

control - power to direct or determine; "under control"

jurisdiction, legal power - (law) the right and power to interpret and apply the law; "courts having jurisdiction in this district"

disposal - the power to use something or someone; "used all the resources at his disposal"

free will, discretion - the power of making free choices unconstrained by external agencies

veto - the power or right to prohibit or reject a proposed or intended act (especially the power of a chief executive to reject a bill passed by the legislature)

reins - power to control; "the reins of government"

effectiveness, effectivity, effectuality, effectualness - power to be effective; the quality of being able to bring about an effect