The Collaborative International Dictionary of English v.0.48:
Surrenderor \Sur*ren`der*or"\, n. (Law) One who makes a surrender, as of an estate. --Bouvier. [1913 Webster]Bouvier's Law Dictionary, Revised 6th Ed (1856):
SURRENDEROR. One who makes a surrender; as when the tenant gives up the estate and cancels his lease before the expiration of the term; one who yields up a freehold estate for the purpose of conveying it.