The word entered English in the early fifteenth century, from Latin. John Lydgate, a monk and one of the most prolific poets of his age, used it in Troy Book, his account of the Trojan War, describing a man trapped so completely he could not escape with his life.
Latin fed the word into English through translation. An anonymous English version of Palladius's De re Rustica, a Roman farming manual, gave the Latin word directly into English around 1425. A translator of Ranulf Higden's Polychronicon did the same shortly after, converting a wicked spirit shut inside a boiling pot.
Two parts built the Latin word, the prefix in-, meaning in or within, and the verb claudere, meaning to shut. Behind that verb lay a Proto-Indo-European root, *klau-, naming a hook, the kind used to lock a door shut in the ancient world.
CLOISTER and CLOSET share the same Latin root. CLOISTER entered English in the thirteenth century, naming a monastery or a place of religious retreat, a space closed off from the world outside. CLOSET arrived a century later, naming a small private room for prayer or study. Old English already had a related word from the same root, meaning prison, or barrier.
For its first two centuries in English the word described confinement, shutting a person or thing away where it could not escape. In 1751 the physician John Hill used it in his History of Materia Medica to group gold, silver, copper, tin, iron, and lead together as a single class of metals. In 1934 a Hollywood producer, said to have struggled with English idioms his whole career, produced one of the most famous phrases in American movie making by rejecting the word entirely and demanding something else instead.
