/klɔːz/
[noun] A separate part of a legal document, contract, or agreement that deals with a specific point; in grammar, a group of words that contains a subject and a verb and forms part of a sentence.
Every legal clause descends from the Latin word for 'closing' — a clause was literally the moment a sentence shut its door.
The story of 'clause' begins in classical Latin with the verb 'claudere', meaning 'to close' or 'to shut'. From this verb came the noun 'clausa', which referred to the closing or ending of something — particularly the conclusion of a rhetorical period or a section of writing. The idea was physical and spatial: a clause was the point at which something was sealed off, finished, and contained.
Medieval Latin scholars picked up 'clausa' and applied it directly to their writing. In the manuscripts of legal scholars and theologians, a 'clausa' described a distinct, self-contained section of text — a unit that opened, made its point, and then closed. This usage passed into Old French as 'clause', keeping the same meaning: a defined portion of a legal or theological document. From Old French 'clause', the word crossed into Middle English in the 13th century, arriving in a world where Latin-based legal language was rapidly reshaping the English tongue.
In its earliest English appearances, 'clause' was used almost exclusively in legal and ecclesiastical writing. Charters, wills, contracts, and church documents were built from clauses — each one a sealed unit of obligation or declaration. This legal meaning has remained remarkably stable for over seven centuries. When you read that a rental agreement contains a 'break clause' or that a treaty includes an 'escape clause', you are using the word in precisely the same sense as a 13th-century English scribe would have understood.
The grammatical sense — a group of words with a subject and a predicate — developed as scholars began to apply the same logic to the structure of language itself. Just as a legal document was divided into self-contained sections, a sentence could be divided into self-contained units of meaning. This grammatical use became firmly established by the 16th century and is now the primary sense most students encounter. The two meanings — legal and grammatical — have always shared the same underlying idea: a bounded, complete unit within a larger whole.
The Latin root 'claudere' is a remarkably productive ancestor in English. It gave Latin 'claustrum' (an enclosed space), which passed into Old French as 'cloistre' and then into English as 'cloister' — the enclosed walkway of a monastery. The same root produced Latin 'conclusio' → Old French 'conclusion' → English 'conclusion', and Latin 'inclusio' → Old French 'inclusion' → English 'inclusion'. Even the word 'close' itself travels the same road: Latin 'claudere' → Old French 'clos' (shut, enclosed) → Middle English 'close'. Every time you close a door, conclude an argument, or read the closing clause of a contract, you are echoing the same ancient Latin act of shutting something firmly in place.