RELICT – a widow or widower; the surviving spouse
Merriam-Webster Online Dictionary
relict (noun)1.
- widow
2.
a surviving species of an otherwise extinct group of organisms , also a remnant of a formerly widespread species that persists in an isolated area
3.
a) a feature or rock remaining after other parts have disappeared - relief
b) something left unchanged
of, relating to, or being a relict - relict populations