Naaphuph (Χ Φ·ΧΦ²Χ€ΧΦΌΧ£) is a noun meaning adultery, fornication, or (frequently) spiritual unfaithfulness/idolatry. It appears in Ezekiel 23:43 in the context of the allegory of Oholah and Oholibah, where Israel's covenant unfaithfulness to Yahweh is portrayed as sexual promiscuity with foreign nations and their gods.
The prophets β especially Hosea, Jeremiah, and Ezekiel β consistently used marital/sexual language to describe Israel's relationship with Yahweh and their covenant violations. Yahweh is the husband; Israel the wife; idolatry is adultery (naaphuph). This metaphor is not arbitrary β it communicates the intimacy and exclusivity of the covenant relationship. Covenant with God is not a contract but a marriage.
Ezekiel 23's graphic allegory forces the reader to confront the ugliness of spiritual unfaithfulness. What feels like harmless cultural accommodation β borrowing the gods of neighboring nations β is exposed as the deepest betrayal. The NT continues this imagery: the church is the Bride of Christ (Ephesians 5:25-27; Revelation 19:7), and James 4:4 calls worldliness "spiritual adultery."