conditional (adj.)

mid-14c., condicioun, "particular mode of being of a person or thing," also "a requisite or prerequisite, a stipulation," from Old French condicion "stipulation; state; behavior; social status" (12c., Modern French condition), from Medieval Latin conditionem (nominative conditio), properly condicio "agreement; stipulation; the external position, situation, rank, place, circumstances" of persons, "situation, condition, nature, manner" of things, from condicere "to speak with, talk together, agree upon," in Late Latin "consent, assent," from assimilated form of com "together" (see con-) + dicere "to speak" (from PIE root *deik- "to show," also "pronounce solemnly").

Classical Latin condicio was confused in Late Latin with conditio "a making," from conditus, past participle of condere "to put together." The sense evolution in Latin apparently was from "stipulation" to "situation, mode of being."

Meaning "rank or state with respect to ordered society" is from late 14c. in English. From the notion of "prerequisite" comes the sense of "a restricting or limiting circumstance" (late 14c.). Also in Middle English "personal character, disposition" (mid-14c.).

1660s, from un- (1) "not" + conditional (adj.). Related: Unconditionally. Unconditional surrender in the military sense is attested from 1730; in U.S., often associated with Civil War Gen. Ulysses S. Grant and the taking of Fort Donelson.

The ringing phrase of Grant's latest despatch circulated through the North like some coinage fresh from the mint, and "Unconditional Surrender," which suited the initials of his modest signature, became like a baptismal name. [James Schouler, "History of the United States of America," Dodd, Mead & Co., 1899].