1590s, "to communicate with another or others in search of mutual agreement," a back-formation from negotiation, or else from Latin negotiatus, past participle of negotiari "carry on business, do business," from negotium "a business, employment, occupation, affair (public or private)," literally "lack of leisure," from neg- "not" (from PIE root *ne- "not") + otium "ease, leisure," a word of unknown etymology.

Transitive sense of "arrange for or procure by negotiation" is from 1610s. In the sense of "handle, manage, tackle successfully" (1862), it at first meant "to clear on horseback a hedge, fence, or other obstacle" and "originated in the hunting-field; those who hunt the fox like also to hunt jocular verbal novelties" [Gowers, 1965]. Related: Negotiated; negotiating.

early 15c., negotiacioun, "a dealing with people, trafficking," from Old French negociacion "business, trade," and directly from Latin negotiationem (nominative negotiatio) "business, traffic," noun of action from past participle stem of negotiari "carry on business, do business, act as a banker," from negotium "a business, employment, occupation, affair (public or private)," also "difficulty, pains, trouble, labor," literally "lack of leisure," from neg- "not" (from PIE root *ne- "not") + otium "ease, leisure," a word of unknown origin.

The sense expansion from "doing business" to also include "bargaining" about anything took place in Latin. Meaning "mutual discussion and arrangement of the terms of a transaction or agreement" is from 1570s.

1590s, "businessman" (a sense now obsolete); c. 1600, "one who carries on negotiations, one who treats with others as either principal or agent;" from Latin negotiator "one who carries on business by wholesale," from negotiatus, past participle of negotiari "carry on business, do business" (see negotiation).

1749, "capable of being negotiated" (of bills, bank notes, etc.), from negotiate + -able, or from French négociable (17c.). Of roads, passages, etc., by 1880. Related: Negotiably; negotiability.

also re-negotiate, "negotiate (a contract, treaty, etc.) again or anew," 1844, from re- "again" + negotiate (v.). Related: Renegotiated; renegotiating; renegotiation.

Proto-Indo-European root meaning "not."

It might form all or part of: a- (3) "not, without;" abnegate; ahimsa; an- (1) privative prefix; annihilate; annul; aught (n.2) "zero, nothing;" deny; hobnob; in- (1) "not, opposite of, without;" ixnay; naught; naughty; nay; nefarious; negate; neglect; negligee; negotiate; neither; nepenthe; nescience; nescient; neuter; never; nice; nihilism; nihility; nil; nill; nimiety; nix; no; non-; none; nonplus; nor; not; nothing; null; nullify; nulliparous; renegade; renege; un- (1) prefix of negation; willy-nilly.

It might also be the source of: Sanskrit a-, an- "not;" Avestan na "not;" Greek a-, an-, ne- "not;" Latin in- "not," ne "that not;" Old Church Slavonic and Lithuanian ne "not;" Old Irish an-, ni, Cornish ny "not;" Gothic and Old English un- "not."

"invested with, having, or bestowing full power," 1640s, from French plénipotentiaire and directly from Medieval Latin plenipotentiarius "having full power," from Late Latin plenipotens, from Latin plenus "complete, full" (from PIE root *pele- (1) "to fill") + potentem "powerful" (see potent). As a noun from 1650s, "person invested with full powers to transact any business," especially with reference to an ambassador to a foreign court or government, given full power to negotiate a treaty or transact other business.

c. 1300, trēten (intrans.), "negotiate, debate or discuss for the purpose of settling a dispute;" late 14c. as "bargain, deal with;" from Old French traitier "deal with, act toward; set forth" in speech or writing (12c.). This is from Latin tractare "manage, handle, deal with, conduct oneself (in a certain manner) toward," literally "drag about, tug, haul, pull violently," frequentative of trahere (past participle tractus) "to pull, draw" (see tract (n.1)). Compare entreat.

The sense of "deal with, handle, or develop in speech or writing" is from early 14c.; in reference to tangible objects, "deal with or touch physically," late 14c. The use in medicine "attempt to heal or cure, to manage in the application of remedies," is by early 15c. (Chauliac); one of the Middle English senses of treat (n.) was "medicinal salve" (late 14c.).

The meaning "entertain with food and drink without expense to the recipient by way of compliment, good will or kindness" is by 1710. Related: Treated; treating.