μοιχεύω

I commit adultery

Definition

The verb μοιχεύω means 'to commit adultery,' specifically referring to sexual infidelity that violates a marriage covenant. In the New Testament, it is used both for a man having relations with a married woman (the most common ancient sense, as in John 8:4) and for a married man being unfaithful (as implied in Jesus's teaching in Matthew 19:9). Jesus radically expands its application in the Sermon on the Mount, declaring that even lustful intent constitutes adultery in the heart (Matthew 5:28). The commandment against adultery is also cited in lists of moral laws (e.g., Mark 10:19, Romans 2:22).

Biblical Usage

Μοιχεύω appears 11 times, primarily in the Gospels and once in Romans. Its usage falls into three main patterns: 1) In legal or catechetical contexts, it cites the Seventh Commandment (e.g., Matthew 19:18, Mark 10:19, Luke 18:20). 2) In Jesus's ethical teaching, it is used to deepen the commandment's requirement to include inward purity (Matthew 5:27-28) and to discuss divorce and remarriage (Luke 16:18). 3) In narrative, it describes the act itself, as in the woman caught in adultery (John 8:4). Paul uses it rhetorically in Romans 2:22 to confront hypocrisy.

Etymology

Derived from the noun μοιχός (moichos, G3432), meaning 'an adulterer.' The verb form μοιχεύω is built on this root, specifically meaning 'to act as an adulterer.' It is part of a word family dealing with marital unfaithfulness, distinct from πορνεύω (porneuō, G4203), which covers broader sexual immorality.

Semantic Range

This word is theologically significant as it touches on covenant faithfulness, the sanctity of marriage, and the depth of God's moral law. Jesus's internalization of the commandment (Matthew 5:28) shifts adultery from a purely external act to a matter of the heart, highlighting humanity's need for inner transformation. It underscores that God's standard concerns not just actions but intentions, relating directly to doctrines of sin, repentance, and the call to holiness. Understanding the Greek term helps readers grasp the comprehensive nature of biblical sexual ethics.

In the first-century Jewish and Greco-Roman world, adultery was primarily defined as a man having sexual relations with a married or betrothed woman, violating another man's marital rights. A married man's relations with an unmarried woman were often not legally considered adultery in Roman law, though Jewish law condemned it. Jesus's teaching challenged these cultural limitations by holding both married men and women to the same standard of fidelity and by focusing on the heart's condition, not just the legal or social offense.

πορνεύω (porneuō, G4203) — a broader term for sexual immorality, including but not limited to adultery. μοιχάομαι (moichaomai, G3429) — a less common synonymous verb for committing adultery.

Word Details

Scripture References