Greek word · G3429

μοιχάω

moichaō

to commit adultery

To commit adultery. Moichaō is a Koine variant of the commoner moicheuō. In the Hebrew Bible, adultery (na'af) meant sex between a married or betrothed woman and a man other than her husband. It was a violation of the husband's marriage.

Appears 4 times in 4 verses of the Greek New Testament. ·

What it means

μοιχάω, -ῶ

(= cl. μοιχεύω), [in LXX (mid., absol. and with accusative, with party of either sex as subj.) : Jeremiah 3:8 5:7 7:9 9:2 23:14 29:23, Ezekiel 16:32 (נָאַף) * ;]

to commit adultery with: with accusative, fem. In NT always mid, in same sense; of the man : absol., Matthew 5:32 19:9 (WH, txt., R, mg., om.); before ἐπ᾽ αὐτήν, Mark 10:11; of the woman: Mark 10:12.†

(AS)

From G. Abbott-Smith, A Manual Greek Lexicon of the New Testament (1922), via STEPBible.org (CC BY 4.0).

In depth

From the study of Matthew 19:9

Range of meaning

To commit adultery. Moichaō is a Koine variant of the commoner moicheuō. In the Hebrew Bible, adultery (na'af) meant sex between a married or betrothed woman and a man other than her husband. It was a violation of the husband's marriage.

Against the English

All major English versions say "commits adultery". The translation is accurate. What modern readers miss is how unexpected it was for the husband to be the adulterer here.

Used elsewhere in the period
  • Septuagint: Jeremiah 3:8 and Ezekiel 16:32 use moichaomai for a wife's unfaithfulness.
  • Leviticus 20:10; Deuteronomy 22:22: the Torah defines adultery around another man's wife. A married man with an unmarried woman was not called adultery.
  • Mark 10:11: the man who remarries "commits adultery against her", meaning against his first wife.

From the study of Mark 10:11

Range of meaning

To commit adultery. In Jewish law and the Hebrew Bible (נָאַף, na'af), adultery meant sex between a man and a woman who was married or betrothed to another man (Leviticus 20:10; Deuteronomy 22:22). It was defined by the woman's marital status. A married man who had sex with an unmarried woman, or who took a second wife, did not commit adultery under that definition, because polygyny was legal.

Against the English

Modern English treats 'adultery' as symmetrical: either spouse can betray the other. Read that way, Jesus' words sound unremarkable. In the first century, saying a husband commits adultery against his own wife changed the usual categories.

How it drifted

Once monogamy and equal marital fidelity became the norm in Christian and later Western law, 'adultery' came to mean any spouse's infidelity. The asymmetry Jesus was addressing is no longer visible.

Used elsewhere in the period

Mark and Matthew use this middle/passive form (Matthew 5:32; 19:9). Elsewhere the active μοιχεύω is more common (e.g., the commandment in Mark 10:19). They mean the same thing. In the Septuagint, μοιχεύω translates na'af. Philo and Josephus discuss adultery as a wrong against the husband's rights over his wife.

Similar words

Where it appears

Matthew · 2

  1. Matthew 5:32 μοιχᾶται.¶ commits adultery.

    But I tell you that anyone who divorces his wife, except for sexual immorality, brings adultery upon her. And he who marries a divorced woman commits adultery.

    Here: 'Commits adultery.' The second husband is said to commit adultery, because in Jesus' view the first marriage is not truly undone by the husband's dismissal.

  2. Matthew 19:9 μοιχᾶται. commits adultery.

    Now I tell you that whoever divorces his wife, except for sexual immorality, and marries another woman commits adultery.”

    Here: Present tense, middle voice, stating a general truth: such a man "commits adultery". The point is that the first marriage still stands before God, so the new union breaks it.

Mark · 2

  1. Mark 10:11 μοιχᾶται commits adultery

    So He told them, “Whoever divorces his wife and marries another woman commits adultery against her.

    Here: 'He commits adultery.' It is present tense, the normal tense for a general rule ('whoever does X is doing Y'). The shock is the subject: under the conventions of the day a husband could not commit adultery against his own wife. Jesus says he does.

  2. Mark 10:12 μοιχᾶται.¶ she commits adultery.

    And if a woman divorces her husband and marries another man, she commits adultery.”

Word data: STEPBible.org (CC BY 4.0), main text only.