Chapter (Latin capitulum) designates certain corporate ecclesiastical bodies in the Roman Catholic, Anglican and Nordic Lutheran churches.
The word is said to be derived from the chapter of the rule book: it is a custom under the Rule of Saint Benedict that monks gather daily for a meeting to discuss monastery business, hear a sermon or lecture, or receive instructions from the abbot, and as the meeting begins with a reading of a chapter from the Rule, the meeting itself acquired the name "chapter," and the place where it is held, "chapter house" or "chapter room."
The term was then extended to apply to other meetings. The term general chapter designates a monastic general assembly, usually of representatives from all of the monasteries of an order or congregation. The "Chapter of Mats" is the term for a similar meeting of representatives of various provinces and subgroups of the Franciscan family of communities. A "chapter of faults" is held regularly by many religious communities at which members are both corrected for infractions against the community's rule, or accuse themselves of their faults and ask for a penance to be prescribed.
From these conventual chapters or meetings of monks for the transaction of business connected with their monasteries or orders, the designation passed over to somewhat analogous assemblies of other ecclesiastics. Hence, one speaks of collegiate chapters and of cathedral chapters, both of which comprise the canons connected to the cathedral or other church ("collegiate" here refers to the "college" or community of canons to whom the church has been entrusted). In general a chapter may be defined as an association of clerics of a certain church forming a moral body and instituted by ecclesiastical authority for the purpose of promoting the divine worship by means of choir service. If it be a cathedral chapter, however, its principal object is to assist the bishop in the government of his diocese, and the choir service is only secondary. Members of chapters are called canons.
This article incorporates text from a publication now in the public domain: Herbermann, Charles, ed (1913). "Chapter". Catholic Encyclopedia. Robert Appleton Company.