Adultery

{{a·dul·ter·y (ə-dŭl'tə-rē, -trē) n. pl. a·dul·ter·ies}}

  Voluntary sexual intercourse between a married person and a partner other than the lawful spouse.

adultery. (n.d.). The American Heritage® Dictionary of the English Language, Fourth Edition. Retrieved April 06, 2007, from Dictionary.com website: http://dictionary.reference.com/browse/adultery

A supplemental note: adultery, as defined by modern American morés, is any kind of sexual activity between a married person and a partner other than his/her lawful spouse.

Insofar as Protestant and Catholic Scripture is concerned, adultery the concept includes ideas and actions like fornication, lust, and physical or emotional intmacy beyond what "appropriate" for a married man or woman.

Adultery is a concept dependent upon one or both individuals involved currently being in a lawfully recognized, contractual, love relationship known as marriage.

Sexual activity before the context of marriage is known as fornication.

"Imaginary" sexual activity outside the context of marriage is known as lust.