Origins
The word 'possible' entered English in the mid-fourteenth century from Old French 'possible,' borrowβββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββed from Latin 'possibilis,' meaning 'that can be done.' Its etymology leads directly to one of the most important conceptual equations in ancient thought: possibility as power.
Latin 'possibilis' derives from the verb 'posse' (to be able, to have power), which is itself a contraction of the archaic phrase 'potis esse' β literally 'to be powerful' or 'to be capable.' The adjective 'potis' meant powerful, able, or capable, and descended from Proto-Indo-European *pΓ³tis, meaning powerful, lord, or master. This root is extraordinarily productive across the Indo-European family: it gave Sanskrit 'pΓ‘ti' (lord, husband, master), Greek 'pΓ³sis' (husband, literally lord), Lithuanian 'pΓ ts' (husband), and Latin 'potis' itself, which generated 'potΔns' (powerful, from which 'potent'), 'potestΔs' (power), and 'potentia' (power, capacity β from which 'potential').
The conceptual chain embedded in this etymology β from power (*pΓ³tis) to ability (posse) to possibility (possibilis) β reveals how the ancients understood the relationship between what is and what might be. Possibility was not conceived as an abstract logical category (as it would become in modern philosophy) but as a function of power: what is possible is what some agent has the power to bring about. The impossible is simply what exceeds all power.
Latin Roots
This power-based concept of possibility was formalized by Aristotle, who distinguished between 'dΓ½namis' (potentiality, capacity, power) and 'enΓ©rgeia' (actuality, activity). An acorn has the 'dΓ½namis' to become an oak; a block of marble has the 'dΓ½namis' to become a statue. When the Latin-speaking medieval scholars translated Aristotle, they rendered 'dΓ½namis' as 'potentia' β from the same root as 'possibilis.' The entire Aristotelian metaphysical framework of potentiality and actuality thus flows through the same etymological channel as the everyday English word 'possible.'
The negative form 'impossible' (from Latin 'impossibilis') entered English at roughly the same time as 'possible,' in the mid-fourteenth century. The prefix 'im-' (a form of 'in-,' meaning not) simply negates the possibility: what is impossible is what no power can accomplish. The word has generated some of history's most famous quotations, from the apocryphal Napoleon ('impossible is a word found only in the dictionary of fools') to Nelson Mandela ('it always seems impossible until it is done').
The related word 'power' itself entered English from Anglo-French 'poer' (from Vulgar Latin *potΔre, a regularization of 'posse'), providing English with a doublet: 'power' from the popular spoken form and 'possible' from the literary Latin form, both ultimately from the same root. 'Potent,' 'potential,' 'omnipotent,' 'impotent,' and 'possess' (from Latin 'possidΔre,' to sit as master) all belong to this same vast family.
Scientific Usage
In modern philosophy, 'possible' has become a technical term of extraordinary precision. Modal logic β the branch of logic that studies necessity and possibility β defines a proposition as 'possible' if it is true in at least one possible world. This framework, developed by Leibniz in the seventeenth century and formalized by Kripke in the twentieth, has made 'possible' one of the most rigorously analyzed words in the philosophical vocabulary. Yet even in this rarefied context, the ancient etymological intuition persists: possibility is about what can be, and 'can' is always, at bottom, a question of power.