bigamy

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. The criminal offense of marrying one person while still legally married to another.

Century Dictionary and Cyclopedia

1. n. Literally, double marriage; remarriage during the existence of a former marriage; in law, the offense of having two or more wives or husbands at the same time. To constitute the offense, which by statute law is a felony, it is necessary, by the law of many jurisdictions, that the accused should have actual or constructive knowledge that the first wife or husband was still living when the second one was taken, and that the second marriage should have been one solemnized under the forms of law, and not merely an informal marriage resting on the contract of the parties, or their holding out each other to the world as husband and wife. Where these elements of knowledge and of formality are wanting, the second marriage is still generally invalid, but not bigamous in the criminal sense.
2. n. . Second marriage; remarriage of a widow or widower. In the early church, before the establishment of clerical celibacy, such remarriage on the part of a man was generally regarded as an impediment to holy orders. Marriage with a widow is called bigamy by Shakspere in Richard III., iii. 7.

Wiktionary

1. n. The state of having two (legal or illegal) spouses simultaneously
2. n. ecclesiastical A second marriage

GNU Webster's 1913

1. n. (Law) The offense of marrying one person when already legally married to another.

WordNet 3.0

1. n. the offense of marrying someone while you have a living spouse from whom no valid divorce has occurred
2. n. having two spouses at the same time