/kənˈvɛnʃən/
[noun] A large formal meeting where people with shared interests come together, or an accepted rule or way of doing something that most people follow without being told to.
Every 'convention' you attend is literally a 'coming together' — the word has never stopped meaning exactly what it meant in ancient Rome.
The story of 'convention' begins in ancient Rome, with the Latin verb *venire*, meaning 'to come'. The Romans were great organizers of people — armies, assemblies, councils — and they needed precise words for the act of gathering. By attaching the prefix *con-* (meaning 'together' or 'with') to *venire*, they created *convenire*, a verb meaning 'to come together', 'to meet', or 'to agree'. From this verb they built the noun *conventio* (in its accusative form, *conventionem*), which described both the physical act of assembling and the agreements that such assemblies produced.
The word passed into Old French as *convention*, carrying both meanings — a gathering and a formal agreement — almost perfectly intact. This was typical of how Latin legal and administrative vocabulary traveled through French into the languages of medieval Europe. When English borrowed the word in the 15th century, it came directly from this Old French form, and the Latin roots were still very much alive in the word's meaning.
In its earliest English uses, 'convention' referred chiefly to formal agreements between parties — what we might today call a treaty or contract. This meaning is preserved in phrases like 'the Geneva Convention', where the word still carries the weight of a solemn, binding accord between nations or groups. The sense of a physical meeting came slightly later, but it was always latent in the word, since agreements naturally arise from people coming together.
Over time, a third strand of meaning quietly wove itself into the word. Because large formal gatherings tend to produce rules, expectations, and shared habits — and because societies develop their own unwritten codes of behaviour through repeated practice — 'convention' began to mean an accepted custom or social norm. By the 18th century, writers were using the word to describe the unspoken rules of polite society, artistic practice, or literary form. A 'convention' in this sense is something everyone follows not because a law demands it, but because it is simply what is done.
What makes 'convention' so durable is that all three of its meanings — gathering, agreement, and custom — flow naturally from the same source. When people *come together* repeatedly, they reach *agreements*, and those agreements harden over time into *customs*. The Latin root *venire* is still quietly alive in a whole family of English words: *venire* → Old French *venir* → English 'venue' (a place people come to); Latin *invenire* ('to come upon') → Old French *inventer* → English 'invent'; Latin *adventus* ('a coming toward') → Old French *avent* → English 'advent'. Every one of these words carries the ghost of ancient Romans moving purposefully toward a meeting place.