chapter (n.) c. 1200, "main division of a book," from Old French chapitre (12c.) "chapter (of a book), article (of a treaty), chapter (of a cathedral)," alteration of chapitle, from Late Latin capitulum "main part, chapter of a book," in Medieval Latin also "a synod or council," literally "little head," diminutive of Latin caput "head," also "leader, guide, chief person; summit; capital city; origin, source, spring," figuratively "life, physical life;" in writing "a division, paragraph;" of money, "the principal sum," from PIE root kaput- "head."