From Latin 'articulus' (small joint), PIE *h₂er- (to fit together) — written sections as the dividing joints of a document.
A piece of writing on a specific subject in a newspaper, magazine, or other publication; a particular item or object; in grammar, a determiner (a, an, the) used before a noun.
From Old French article, from Latin articulus (a small joint, a division, a clause, a short time), a diminutive of artus (a joint, a fitting, a limb), from PIE *h₂er- (to fit together, to join). The PIE root *h₂er- is foundational to the language of craft and order: Latin arma (weapons, that which is fitted to the body), ars/artis (skill, art — the fitting together of things with expertise), armāre (to equip), articulus, articulāre (to connect, to speak distinctly). Greek armós (joint) and arti (just, exactly) are cognate. The semantic history
The grammatical meaning of 'article' (words like 'the' and 'a') comes directly from the body-part metaphor: Greek grammarians called these words 'arthra' (joints) because they were seen as the connective tissue that joins nouns to the rest of a sentence, just as joints connect bones in the body.