Ability, authority, and energy
In present-day English, power covers several ideas that still share one core: the capacity to produce an effect. It can mean bodily strength, the right to command, political control, or the energy that drives a machine. A state with global reach is called a power; so is the current that keeps a city lit. The origin of the word power is a medieval French loan, not a native Germanic inheritance. English took it in already carrying a cluster of legal, military, and physical senses, then kept adding new ones as technology and politics changed.
The everyday native rival is might, from Old English miht. That word never disappeared. What the French loan offered was a broader, more official-sounding noun for capacity, command, and force, one that later proved easy to stretch into science and engineering.
A French infinitive treated as a noun
Around 1300, Middle English scribes were writing pouer, poer, poeir, and power. Those spellings follow Anglo-French pouair and poer, and Old French poeir, pooir, and povoir. In French the form began as a verb meaning to be able. Speakers then used that infinitive as a noun: not only the act of being able, but ability itself. Modern French still does this with pouvoir, which remains both verb and noun. The earliest English evidence sits near 1300, in a Middle English life of St James the Great.
The loan entered a language that already had words for rule. Old English anweald, later Middle English anwald or onwald, meant authority and the capacity to govern. The French loan displaced that native term. Might stayed; anweald did not. The new word also arrived with senses that the older vocabulary handled less neatly, including legal authorization and a body of armed men.
The shape of the loan is worth a moment. English did not borrow a typical noun ending and then build a verb from it. It borrowed a verb form that French had already turned into a name for the ability. That is why the English noun sits so close, historically, to a Romance verb of capability.
Latin ability and a reconstructed spoken verb
Behind the French forms stands Vulgar Latin *potere, a reconstructed verb that replaced classical Latin posse, to be able. The asterisk matters: *potere is inferred from later Romance words rather than quoted from a classical author. Spanish poder and Italian potere continue that spoken Latin verb and, like French, still use it as both verb and noun. Classical posse is itself a tight compound of potis, able or powerful, and esse, to be.
Latin potis belongs to a wider Indo-European set. The reconstructed root, written *poti- or *pótis, is given the senses powerful and lord. Relatives commonly cited outside Latin include Sanskrit patih, master or husband; Greek posis, husband; and Lithuanian patis, husband. English did not receive power along a Germanic line from that root. The path is French, then spoken Latin, then the classical adjective of ability.
Other English words keep the same Latin stem without being descendants of the noun power. Potent, potency, potential, possible, possess, and the older French-derived puissant all point back to potis or posse by different routes. They are cousins, not children, of the Middle English loan.
Sources line up on this outline, with one difference of emphasis rather than a real clash. Some dictionaries step from the French infinitive to *potere and then to posse. Others skip posse and name potis as the Latin source. Both descriptions are compatible: posse is potis plus the verb to be, and *potere is the later spoken reshaping of that idea of being able.
How the senses accumulated
The first English uses were already crowded. The word could mean the ability to act, vigor, especially in battle, mastery and dominion, a legal right to command, an authorization, and a military force. By the late fourteenth century it could name a person who held authority. Early in the fifteenth it could mean a particular faculty: a power of speech, of memory, of persuasion.
Later centuries stacked technical layers on that base instead of replacing it. By the 1590s writers applied the noun to inanimate agents. A medicine, a magnet, or a storm had power because it changed something else. In the 1660s a power of could mean a large amount, a sense that still turns up in some regional English. By 1726 a power could be a state judged by its international weight. Around 1727, in mechanics, it named that with which work can be done, and more broadly the energy available for work. Electrical supply is a late specialization, attested by 1896.
The verb trailed the noun. An earlier sense, to make someone powerful, is recorded in the 1530s. To supply a device with energy dates from 1898, after the electrical meaning of the noun was in place. Compounds followed the same industrial turn: power failure by 1911, power steering by 1921.
A few set phrases keep the older political coloring. The powers that be, for the authorities in charge, comes from the English of Romans 13:1. More power to someone, as a wish of success, is recorded from 1842. Power politics, for policy backed by the threat of force, entered English in the 1930s as a rendering of German Machtpolitik.
Mathematics uses the same English noun for an exponent and for the result of raising a number to that exponent. That is not a separate etymology. Sixteenth-century English Euclid translations, including Henry Billingsley's 1570 version, used power for a line's square, following Greek dynamis. The mathematical meaning is a technical reuse of the ordinary word, not a new borrowing from Latin.
What the Romance cousins still show
French pouvoir, Spanish poder, and Italian potere remain both verbs of ability and nouns of capacity. English kept mainly the noun, then stretched it from battlefield might to wattage. The buried Latin idea is simply being able. Armies, parliaments, and wall sockets are later applications of that one fact.
If a single dating is worth carrying away, it is the first English century of the loan. By about 1300 the word already meant strength, legal right, and an army. Electricity, horsepower, and the great powers of Europe are modern specializations of a French infinitive that had already learned to name ability as a thing.