Synonyms for Potency:

n.

leadership, monopoly, oligopoly, greatness. injection, Thew, drug, o.d., dose, Medicated, off, contraindication, Narcotics, sinew, on, dosage, strong. get-up-and-go, go, peppiness, action. efficiency, efficaciousness, efficacy, affect, effect. authority (noun)
faculty, birthright, credential, stature, cogency, right, primacy, domination, clout, powerfulness, mightiness, empowerment, command, license, kingship, office, precedence, seniority, superiority, prestige, commission, mandate, purview, sovereignty, control, privilege, enfranchisement, charge, prerogative, mastery, Prepotency, sway, authority, punch, rank, entitlement, title, influence, steam.
effectiveness (noun)
go, control, might, sinew, power, authority, pep, command, influence, efficacy, efficiency, zip, energy, force, potential, puissance, snap, dominion, zing, vigor, punch, strength, sway, muscle, steam.
efficacy (noun)
efficacy.
energy (noun)
power, vigor, force, snap, fire, verve, vim, effervescence, zeal, spunk, fervor, spark, drive, energy, might, activity, pep, vivacity, zip, zing, spirit, puissance, strength, stamina.
influence (noun)
effectiveness.
maturity (noun)
manhood.
potency (noun)
potential, potentiality, strength, effectiveness.
power (noun)
competence, grasp.
sexual activity (noun)
encounter, blow job, bonk, coitus, coupling, buggery, climax, ejaculation.
strength (noun)
muscle, stoutness, vitality, toughness, stability, brawn, firmness, sturdiness, huskiness.
vigor (noun)
excitement, industriousness, animation, earnestness, friskiness, fervency, passion, lustiness, relish, eagerness, Ardency, liveliness, zest, gusto, agility, agitation, sprightliness, exuberance, enthusiasm.

Other synonyms:

efficaciousness, Thew. get-up-and-go, manhood, peppiness, efficiency. effect, sinew. effectiveness
effectiveness, efficacy.
Other relevant words:
effect, coitus, action, greatness, injection, affect, ejaculation, buggery, go, monopoly, contraindication, leadership, off, effectiveness, coupling, peppiness, get-up-and-go, efficacy, encounter, oligopoly, dominion, potential, sinew, on, Narcotics, dose, potentiality, bonk, Thew, dosage, Medicated, efficiency, strong, climax, efficaciousness, drug, manhood.