from Wiktionary, Creative Commons Attribution/Share-Alike License
- v. To separate, as sisters; to disjoin.
from the GNU version of the Collaborative International Dictionary of English
- transitive v. To separate, as sisters; to disjoin.
from The Century Dictionary and Cyclopedia
- To deprive of a sister; separate, as sisters.
un- + sister (Wiktionary)
Ay, that was in her hour of joy; there will be plenty to sunder and unsister them again: this Gardiner for one, who is to be made Lord Chancellor, and will pounce like a wild beast out of his cage to worry Cranmer.