means The power, strength, or effectiveness something has — its capacity to produce a strong effect, whether a drug, an argument, or a person's influence.

from From Latin potentia, "power, ability," built on potens, the present participle of posse, "to be able" — the same deep root that gives us potent, potential, omnipotent, and even possible. Posse itself is a worn-down fusion of potis, "able, capable, master," and esse, "to be": literally "to be capable." The English word arrived through that long Latin line in the late medieval period, carrying the bare idea of being-able into every shade from medicine to majesty.