late 14c., jupartie , ioparde, etc., "danger, risk;" earlier "a cunning plan, a stratagem" (c. 1300), from or based on Old French jeu parti "a lost game," more correctly "a divided game, game with even chances" (hence "uncertainty"). The sense perhaps developed in Anglo-French.
This is from jeu "a game" (from Latin iocus "jest;" see joke (n.)) + parti, past participle of partir "to divide, separate" (10c.), from Latin partire/partiri "to share, part, distribute, divide," from pars "a part, piece, a share" (from PIE root *pere- (2) "to grant, allot"). Jeopardous "in peril" (mid-15c.) is now obsolete.
*perə-, Proto-Indo-European root meaning "to grant, allot" (and reciprocally, "to get in return"); possibly related to *pere- (1) "to produce, procure."
It forms all or part of: apart; apartment; bipartient; bipartisan; bipartite; compartment; depart; department; ex parte; impart; jeopardy; multipartite; parcel; parse; part; partial; participate; participation; particle; particular; particulate; partisan; partition; partitive; partner; party; portion; proportion; quadripartite; repartee; tripartite.
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit purtam "reward;" Hittite parshiya- "fraction, part;" Greek peprotai "it has been granted;" Latin partem (nominative pars) "a part, piece," portio "share, portion."
"danger, risk, hazard, jeopardy, exposure of person or property to injury, loss, or destruction," c. 1200, from Old French peril "danger, risk" (10c.), from Latin periculum "an attempt, trial, experiment; risk, danger," with instrumentive suffix -culum and first element from PIE *peri-tlo-, suffixed form of root *per- (3) "to try, risk."
early 13c., "scales, apparatus for weighing by comparison of mass," from Old French balance "balance, scales for weighing" (12c.), also in figurative sense; from Medieval Latin bilancia, from Late Latin bilanx, from Latin (libra) bilanx "(scale) having two pans," possibly from Latin bis "twice" (from PIE root *dwo- "two") + lanx "dish, plate, scale of a balance," which is of uncertain origin.
The accounting sense "arithmetical difference between the two sides of an account" is from 1580s; the meaning "sum necessary to balance the two sides of an account" is from 1620s. The meaning "what remains or is left over" is by 1788, originally in commercial slang. The sense of "physical equipoise" is from 1660s; that of "general harmony between parts" is from 1732.
Many figurative uses are from the Middle English image of the scales in the hands of personified Justice, Fortune, Fate, etc.; thus in (the) balance "at risk, in jeopardy or danger" (c. 1300). Balance of power in the geopolitical sense "distribution of forces among nations so that one may not dominate another" is from 1701. Balance of trade "difference between the value of exports from a country and the value of imports into it" is from 1660s.
c. 1300, "twice as much or as large," also "repeated, occurring twice," also "of extra weight, thickness, size, or strength; of two layers," from Old French doble (10c.) "double, two-fold; two-faced, deceitful," from Latin duplus "twofold, twice as much," from duo "two" (from PIE root *dwo- "two") + -plus "more" (see -plus).
From early 14c. as "having a twofold character or relation," also "consisting of two in a set together; being a pair, coupled." From mid-14c. as "characterized by duplicity." The earliest recorded use in English is c. 1200, in double-feast "important Church festival."
Double-chinned is from late 14c.; double-jointed, of persons, is by 1828. Military double time (1833) originally was 130 steps per minute; double quick (adj.) "very quick, hurried" (1822) originally was military, "performed at double time."
The photographic double exposure is by 1872. The cinematic double feature is by 1916. Double figures "numbers that must be represented numerically by two figures" is by 1833. Double-vision is by 1714. Double indemnity in insurance is by 1832; double jeopardy is by 1817. The baseball double play is by 1866.
Double trouble "twice the trouble" is by 1520s; in 19c. America it was the name of a characteristic step of a rustic dance or breakdown, derived from slave dancing on plantations. A double-dip (n.) originally was an ice-cream cone made with two scoops (1936); the figurative sense is by 1940. Double bed "bed made to sleep two persons" is by 1779. Double life "a sustaining of two different characters in life" (typically one virtuous or respectable, the other not) is by 1888.