Koinonia () is a transliterated form of the Greek word κοινωνία, which refers to concepts such as fellowship, joint participation, partnership, the share which one has in anything, a gift jointly contributed, a collection, a contribution. In Christianity it identifies the idealized state of fellowship and unity that should exist within the Christian church, the Body of Christ. Its gifts from the Holly Spirt that embraces and empowers you do to all things. In the Politics of Aristotle it is used to mean a community of any size from a single family to a polis. As a polis, it is the Greek for republic or commonwealth. This usage may have been borrowed from the early Epicureans—as it is used by Epicurus' Principal Doctrines 37–38.

The term communion, derived from Latin communio ('sharing in common'), is related. The term "Holy Communion" normally refers to the Christian rite also called the Eucharist.