Relict

A relict is the surviving spouse upon the death of the other partner, either husband or wife. The word refers to the survivor of the marriage union, not to the survivor of the other person -- as is commonly thought.

The word relict is the opposite of the word consort, in the sense that a marriage is a consortium of husband and wife, hence each is a consort only while the marriage union survives.

Source: Black's Law Dictionary, 4th Edition.