What speakers use it for
In present-day English, possible does two jobs that sit close together and are easy to mix. One job is modal: an event or state of affairs may happen or be true, without being guaranteed. Tomorrow’s rain is possible; a square circle is not. The other job is practical: a task can be carried out, given time, skill, or tools. Learning a language is possible. A third, thinner use turns up in lists and shortlists, where a person or a site is a possible for a job or a plan — still in contention, not yet chosen.
Those senses feel native because the word is so common. Historically it is not a home-grown English formation. It is a medieval loan that arrived already assembled.
Into Middle English by two doors
The origin of the word possible belongs to later Middle English. References that survey the adjective often place it in the mid-fourteenth century. The Oxford English Dictionary’s earliest firm citation is a little later, around 1384, in the early Wycliffite Bible. Both dates sit in the same period; the gap is a matter of which surviving text counts as first, not of a different story.
The word did not rise from Old English. It was borrowed. The immediate sources are Old French possible and Latin possibilis, an adjective meaning, in effect, that something can be done. Historical dictionaries treat the English form as having more than one parent at once: partly French, partly Latin. That double credit is not a fudge. Clerks, translators, and preachers in fourteenth-century England moved between the two languages as a matter of course, and the French and Latin spellings were nearly the same. Taking the word from a French page or from a Latin one would have felt like the same act.
French already had the adjective by about 1265. Anglo-Norman writing shows it soon after, including in legal prose about conditions that might or might not be fulfilled. English inherited a finished Romance adjective, not a root that speakers then fitted with an English ending.
A Latin verb of being able
The Latin piece is easy to take apart. Possibilis joins posse, to be able, with the suffix -bilis, the source of English -ble. The suffix marks a thing as fit to undergo or allow an action. The whole adjective therefore names capacity: able to be done, able to exist.
Posse itself is a contraction of potis esse, to be powerful or to be master. That potis belongs to an Indo-European family reconstructed around a root *poti-, a word for a person with power, a master, or a husband. Sanskrit patih, Greek posis, and Lithuanian patis sit on the same line. Latin kept a large cluster from it: potis, the later English loans potent and potential, possess, and the legal posse. Possible is the member that attaches ability to events and plans rather than to persons.
Imperial Latin already used possibilis in the sense that passed into Romance. French possible, Italian possibile, Spanish posible, Portuguese possível, Catalan possible, and Romanian posibil are siblings of the English adjective. English did not invent the form and then export it; it joined a family that Latin had already spread.
Native words that lost the job
English was not silent on the idea before the loan. Old English had ācumendlīċ, which survived into Middle English as acumendlic and then faded. Another native adjective, mihtelīċ, covered strong, capable, and possible. It belongs with German möglich and Dutch mogelijk, all built on a Germanic word for might or power.
Those Germanic adjectives are parallels, not relatives of possible. They grew from a native noun of strength. The Romance word grew from a Latin verb of being able. Later medieval English often preferred the Latinate option in learned and written registers, and the homegrown forms gave way. The replacement is a change of vocabulary, not a change in what people needed to say.
May happen, can be done, and a noun
Once the adjective was in English, its range widened more than it reversed. The oldest layer is still the modal one: what may be, as against what must be or cannot be. A second layer treats the word as a synonym of feasible. Commentators have sometimes tried to keep those layers apart, reserving possible for what may occur and using other adjectives for what can actually be carried out. Ordinary speech never held the line. English still allows both It is possible that she is late and It is possible to finish by Friday.
By the 1640s the adjective had a noun use: a possible as something that might come into being, or, more loosely, a candidate still on a list. French had already used possible as a noun for what one can do, in phrases of the faire le possible type, in the late fifteenth century. English developed its own noun without needing that exact idiom, though both sit in the same neighborhood of capacity turned into a thing.
Later stock phrases — as soon as possible, humanly possible, the art of the possible — show how thoroughly the loan settled into planning and everyday English. They do not alter the etymology. They show a scholarly adjective becoming ordinary.
Morphology stayed visible. Possibility and possibly are built on the same stem. Impossible is the negative counterpart, with the Latin prefix in- rather than a native un- (though unpossible had a brief life). The family is consistent: English kept the Latin pieces and used them as English pieces.
One date, and a lost rival
The fact worth keeping is the crowded doorway. Possible looks, in the mouth, like a simple French loan, and in speech it is. On the page it is also a Latin word that a fourteenth-century translator could have lifted straight from possibilis. Around 1384 the early Wycliffite Bible gives the citation many historical dictionaries treat as the first solid English foothold, with other surveys willing to push the adjective a few decades earlier.
English already had words for the same idea. They lost. The Romance form won, and with it a small set of English derivatives built on a Latin verb that once meant, quite plainly, to be able.