noun: (uncountable) Associating, or coming together in a union; (countable) an instance of this.
noun: (uncountable) Intimate companionship or fellowship; (countable) an instance of this.
noun: (countable, Christianity) A confederation of Christian churches or organizations.
noun: (US, Congregationalism, specifically) A voluntary, permanent council made up of representatives of neighbouring Congregational churches for mutual advice and co-operation in ecclesiastical matters; also, a meeting of pastors and delegates from churches thus united.
noun: (countable, ecology) A subdivision of an association, made up chiefly of organisms of a single species.
noun: (countable, politics) A power-sharing arrangement over territory entered into by competing groups.
noun: (countable, obsolete) An alliance; a confederation.