/ˈkæʒuəl/
[adjective] Relaxed and not formal, or happening by chance without being planned. For example, a casual meeting is one that was not arranged in advance, and casual clothes are comfortable and not meant for special occasions.
The word 'casual' originally had nothing to do with clothes or attitude — it meant something closer to 'struck by fate'.
At the heart of 'casual' lies the Latin word 'casus', meaning a fall, a chance event, or something that simply happens to you — as if dropped from the sky. This noun came from the Latin verb 'cadere', meaning 'to fall', a root of surprising power and reach. From 'casus', medieval Latin formed the adjective 'casualis', meaning 'subject to chance' or 'accidental'. That Latin adjective passed into Old French as 'casuel', and from there it crossed into English in the late 14th century, arriving in a world still shaped by the idea that fortune was an unpredictable, falling thing.
In its earliest English uses, 'casual' meant exactly what its Latin parent suggested: accidental, happening by chance, or without design. A 'casual encounter' was not a relaxed one — it was an unplanned one, a meeting that fate had arranged rather than any human hand. This sense of randomness and contingency was the word's primary meaning for a long time, and it still survives today when we talk about 'casual workers', people hired without a permanent contract, subject to the unpredictable needs of an employer.
The shift toward the meaning of 'relaxed' or 'informal' came gradually, moving through the idea that something unplanned is also something not prepared for, not dressed up for, not treated with great seriousness. By the 19th century, 'casual' had begun to describe behaviour that was unconcerned or offhand — a casual glance, a casual remark. The connection was logical: if you did not plan something, you did not put effort into it, and so 'casual' came to suggest ease, looseness, and a lack of formality.
The root 'cadere' — to fall — is one of the most productive in the entire English language, and tracing its descendants reveals just how widely a single Latin verb can scatter its seeds. Latin 'cadere' gave rise to 'casus' (a fall, a chance) → Old French 'cas' → English 'case' (a situation, an instance). The same Latin root produced 'accidere' (to fall upon, to happen) → Late Latin 'accidentalis' → Old French 'accident' → English 'accident'. It also gave us Latin 'incidere' (to fall into) → Old French 'incident' → English 'incident', and Latin 'occidere' (to fall down, to set, as the sun falls) → English 'occident', meaning the west, where the sun falls.
Perhaps the most poetic of all these descendants is 'cadence', the rhythmic rise and fall of sound or movement, which came through Latin 'cadentia' → Italian 'cadenza' → Old French 'cadence' → English 'cadence'. Even the word 'chance' itself shares this ancestry: Latin 'cadere' → Vulgar Latin 'cadentia' → Old French 'cheance' → English 'chance'. So when you dress casually for a chance encounter, you are — in the deep memory of the language — twice touched by the same falling Latin verb.
Today 'casual' lives comfortable lives in several different worlds at once. In fashion, 'casual wear' means comfortable, everyday clothing. In employment, a 'casual contract' means irregular, unguaranteed work. In conversation, a 'casual tone' suggests ease and familiarity. And yet underneath all these modern uses, the old Latin shadow remains — the sense that something casual is something that was not fixed in advance, something that, like fate itself, simply fell into place.