legal separation

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun An arrangement terminating the rights and responsibilities of marriage and providing for the disposition of marital property, alimony, and child custody. Unlike a divorce, a legal separation can be revoked, but also may be converted into a divorce in the absence of reconciliation.
• noun A court order establishing this arrangement.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a judicial decree regulating the rights and responsibilities of a married couple living apart
• noun (law) the cessation of cohabitation of man and wife (either by mutual agreement or under a court order)