extramarital

What it means

1. not comparableOccurring outside marriage.

   Synonyms: illegitimate, extraconjugal, extramarriage, extracurricular

2. not comparableAdulterous.

   David H. Petraeus, the director of the Central Intelligence Agency and one of America’s most decorated four-star generals, resigned on Friday after an F.B.I. investigation uncovered evidence that he had been involved in an extramarital affair.

   2012 November 9, Michael D. Shear, “Petraeus Quits; Evidence of Affair Was Found by F.B.I.”, in New York Times

In a sentence

David H. Petraeus, the director of the Central Intelligence Agency and one of America’s most decorated four-star generals, resigned on Friday after an F.B.I. investigation uncovered evidence that he had been involved in an extramarital affair.

2012 November 9, Michael D. Shear, “Petraeus Quits; Evidence of Affair Was Found by F.B.I.”, in New York Times

Where it comes from

1. Proto-Indo-European*h₁éǵʰ
2. Proto-Indo-European*h₁éǵʰs
3. Proto-Indo-European*h₁eǵʰsteros
4. Proto-Italic*eksteros
5. Latinexter
6. Latinextrā
7. Englishextra-
8. Englishmarital
9. Englishextramarital

From extra- + marital.