### Core Meaning & Semantic Range
The Greek word **moicheúō**, represented by `{{G3431}}`, is a direct term meaning **to commit adultery**. It appears **22 times** across **11 unique verses**, primarily serving as a key prohibition within biblical law and moral teaching. Its use establishes a clear standard for marital fidelity.
### Biblical Occurrences & Contextual Analysis
In scripture, `{{G3431}}` is most frequently cited as one of the core commandments. It is consistently listed alongside prohibitions such as "Do not kill," "Do not steal," and "Do not bear false witness" ([[Mark 10:19]], [[Romans 13:9]]). Jesus references this command directly, first by quoting the law as it was known "by them of old time" [[Matthew 5:27]], and then by expanding its meaning. He teaches that anyone who looks at a woman to lust after her has already committed adultery in his heart [[Matthew 5:28]]. The term is also applied to situations of divorce and remarriage, where marrying a person who has been put away from their spouse is defined as committing adultery [[Luke 16:18]].
### Related Words & Concepts
Several related words help clarify the scope and context of committing adultery:
* `{{G1937}}` **epithyméō** (to set the heart upon, i.e. long for (rightfully or otherwise):--covet, desire, would fain, lust (after)): This word is crucially linked to adultery by redefining the sin not just as a physical act but as an internal desire. To **lust after** a woman is equated with having already committed adultery in the heart [[Matthew 5:28]].
* `{{G630}}` **apolýō** (to free fully, i.e. (literally) relieve, release, dismiss (reflexively, depart), or (figuratively) let die, pardon or (specially) divorce): This term for divorce is directly connected to adultery. To **put away** a spouse and marry another is to commit adultery [[Luke 16:18]].
* `{{G5407}}` **phoneúō** (to be a murderer (of):--kill, do murder, slay): This command is often paired with the prohibition against adultery. Its inclusion highlights how adultery is seen as a serious transgression on par with murder [[James 2:11]].
* `{{G3848}}` **parabátēs** (from παραβαίνω; a violator:--breaker, transgress(-or)): This describes the status of one who breaks the law. A person who does not commit adultery but does kill has still become a **transgressor** of the law [[James 2:11]].
### Theological Significance
The theological weight of `{{G3431}}` is significant, defining both sin and righteousness.
* **The Internalization of Law:** The concept of adultery is elevated from a mere external action to a matter of internal purity. Jesus' teaching makes it clear that sin begins in the heart with lustful desire [[Matthew 5:28]].
* **The Unity of the Law:** Adultery is used as a prime example to illustrate that God's law is a single, unified whole. To break one commandment is to be guilty of breaking all of them, making one a **transgressor** of the law [[James 2:11]].
* **Consequences and Repentance:** The act of committing adultery is shown to have severe spiritual consequences, leading to "great tribulation" for those who do not repent of their deeds [[Revelation 2:22]].
* **Hypocrisy Exposed:** The command is used rhetorically to expose religious hypocrisy. One who teaches that others should not **commit adultery** while doing so themselves is condemned [[Romans 2:22]].
### Summary
In summary, `{{G3431}}` is far more than a simple prohibition. It is a cornerstone of biblical morality that defines the sanctity of the marital covenant. Its meaning is expanded from a physical transgression to a sin of the heart, establishing a higher standard of righteousness. As a key component of the law, it illustrates the nature of sin, the necessity of internal purity, and the serious consequences of violating God's commands.
TRV