Online Etymology Dictionary

precarious (adj.): 1640s, a legal word, "held through the favor of another," from Latin precarius "obtained by asking or praying," from prex (genitive precis) "entreaty, prayer" (see pray). Notion of "dependent on the will of another" led to extended sense "risky, dangerous, uncertain" (1680s). "No word is more unskillfully used than this with its derivatives. It is used for uncertain in all its senses; but it only means uncertain, as dependent on others ..." [Johnson]. Related: Precariously; precariousness.
precatory (adj.): 1630s, from Late Latin precatorius "pertaining to petitioning," from precatorem "one who prays," agent noun from precari "to pray" (see pray).
precaution (n.): c.1600, from French précaution (16c.) and directly from Late Latin praecautionem (nominative praecautio) "a safeguarding," from past participle stem of Latin praecavere "to guard against beforehand," from prae "before" (see pre-) + cavere "to be one's own guard" (see caution (n.)). The verb meaning "to warn (someone) in advance" is from c.1700.
precautionary (adj.): 1720, from precaution + -ary.
precautious (adj.): 1680s, from precaution + -ous. Related: Precautiously; precautiousness.
precede (v.): early 15c., "lead the way; occur before," from Middle French preceder and directly from Latin praecedere "to go before," from prae "before" (see pre-) + cedere "to go" (see cede). Meaning "to walk in front of" is late 15c.; that of "to go before in rank or importance" is attested from mid-15c. Related: Preceded; preceding.
precedence (n.): late 15c., "a being a precedent," from precedent (n.) + -ence. Meaning "fact of preceding another, right of preceding another" is from c.1600.
precedent (n.): early 15c., "case which may be taken as a rule in similar cases," from Middle French precedent, noun use of an adjective, from Latin praecedentum (nominative praecedens), present participle of praecedere "go before" (see precede). Meaning "thing or person that goes before another" is attested from mid-15c. As an adjective in English from c.1400. As a verb meaning "to furnish with a precedent" from 1610s, now only in past participle precedented.
precedented (adj.): 1650s, past participle adjective from precedent, which is attested as a verb from 1610s.
precent (v.): "to lead others in singing," 1732, from Latin praecantare "to sing before," or a back-formation from precentor.
precentor (n.): 1610s, from Late Latin praecentor "a leader in singing," from Latin praecantare "to sing before," from prae "before" (see pre-) + canere "to sing" (see chant (v.)). For change of vowel, see biennial.
precept (n.): late 14c., from Old French percept, percet (12c.), from Latin praeceptum "maxim, rule of conduct, order," noun use of neuter past participle of praecipere "give rules to, order, advise," literally "take beforehand," from prae "before" (see pre-) + capere (past participle captus) "to take" (see capable). For change of vowel, see biennial.
preception (n.): 1610s, from Latin praeceptionem (nominative praeceptio) "a previous notion, preconception," literally "a taking beforehand," noun of action from past participle stem of praecipere (see precept).
preceptor (n.): early 15c., "tutor, instructor" (earliest reference might be to "expert in the art of writing"), from Latin praeceptor "teacher, instructor," agent noun from praecipere (see precept). Medical training sense attested from 1803.
preceptorship (n.): 1764, from preceptor + -ship.
precession (n.): 1590s, from Late Latin praecissionem (nominative praecissio) "a coming before," from past participle stem of Latin praecedere "to go before" (see precede). Originally used in reference to calculations of the equinoxes, which come slightly earlier each year.
precieuse (n.): "pedantic woman, woman aiming at refined delicacy of language and taste" (1727), from French précieuse, noun use of fem. of précieux (see precious (adj.)); especially as lampooned in Molière's comedy "Les Précieuses ridicules" (1659).
precinct (n.): c.1400, prasaynt (mid-15c. as precincte), "district defined for purposes of government or representation," from Medieval Latin precinctum "enclosure, boundary line," noun use of neuter past participle of Latin praecingere "to gird about, surround," from prae- "before" (see pre-) + cingere "to surround, encircle" (see cinch (v.)).
precious (adj.): mid-13c., from Old French precios "precious, costly, honorable, of great worth" (11c., Modern French précieux), from Latin pretiosus "costly, valuable," from pretium "value, worth, price" (see price (n.)). Meaning "over-refined" in English first recorded late 14c. In Johnson's day, it also had a secondary inverted sense of "worthless." Related: Preciously; preciousness.
precious (n.): "beloved or dear person or object," 1706, from precious (adj.).
precipe (n.): 1610s, from Latin praecipes, variant of praeceps "headfirst, headlong, precipitous," as a noun, "a precipice" (see precipice).
precipice (n.): "steep face of rock," 1630s, from Middle French précipice, from Latin praecipitium "a steep place," literally "a fall or leap," from praeceps (genitive praecipitis) "steep, headlong, headfirst," from prae "before, forth" (see pre-) + caput "head" (see head (n.)). Earlier in English as a verb (1590s) meaning "fall to great depth."
precipitant (adj.): 1610s, from Latin precipitantem, present participle of praecipitare (see precipitate (v.)). As a noun in chemistry from 1680s. The adjective senses now are taken by precipitate (adj.).
precipitate (v.): "to hurl or fling down," 1520s, a back formation from precipitation or else from Latin praecipitatus, past participle of praecipitare "to throw or dive headlong," from praeceps "steep, headlong, headfirst" (see precipice). Meaning "to cause to happen, hurry the beginning of" is recorded from 1620s. Chemical sense is from 1620s; meteorological sense first attested 1863. Related: Precipitated; precipitating.
precipitate (adj.): c.1600, from Latin praecipitatus, past participle of praecipitare "to throw or dive headlong" (see precipitate (v.)). Meaning "hasty" is attested from 1650s. Related: Precipitately.
precipitate (n.): 1560s, probably a back formation from precipitation.
precipitation (n.): late 15c., "a casting down" (of the evil angels from heaven), also, in alchemy "separation of a solid substance from a solution," from Middle French precipitation (15c.) and directly from Latin praecipitationem (nominative praecipitatio) "act or fact of falling headlong, haste," noun of action from past participle stem of praecipitare "fall, be hasty," from praeceps "steep" (see precipice). Meaning "sudden haste" is c.1500. Meaning "act of falling from a height" is attested from 1610s. Meteorological sense of "rain, snow, dew, etc." is from 1670s.
precipitious (adj.): 1610s, now obsolete, but prefered by purists for the sense "high and steep" over the later formation precipitous.
precipitous (adj.): 1640s, "rash, headlong," from obsolete French precipiteux (16c.), from Vulgar Latin *praecipitosus, from praecipitare (see precipitation). Related: Precipitously; precipitousness.
precis (n.): 1760, from French noun use of Middle French précis "cut short, condensed" (see precise). As a verb, from 1856.
precise (adj.): mid-15c., from Middle French précis "condensed, cut short" (14c.) and directly from Medieval Latin precisus, from Latin praecisus "abrupt, abridged, cut off," past participle of praecidere "to cut off, shorten," from prae "before" (see pre-) + caedere "to cut" (see -cide; for Latin vowel change, see acquisition). Related: Precisely (late 14c.).
preciseness (n.): "precision," 1560s, from precise + -ness.
precisian (n.): "one devoted to precision," 1570s, from precise + -ian on model of Christian, etc.
precision (n.): 1630s, "a cutting off (mentally), abstraction," from French précision (16c.) and directly from Latin praecisionem (nominative praecisio) "a cutting off," noun of action from past participle stem of praecidere (see precise). Meaning "preciseness" is from 1740.
preclude (v.): 1610s, from Latin praecludere "to close, shut off; hinder, impede," from prae- "before, ahead" (see pre-) + claudere "to shut" (see close (v.)). Related: Precluded; precluding.
preclusion (n.): 1610s, from Latin praeclusionem (nominative praeclusio) "a shutting off," noun of action from past participle stem of praecludere (see preclude).
precocious (adj.): 1640s, "developed before the usual time" (of plants), with -ous + Latin praecox (genitive praecocis) "maturing early," from prae "before" (see pre-) + coquere "to ripen," literally "to cook" (see cook (n.)). Originally of flowers or fruits. Figurative use, of persons, dates from 1670s. Related: Precociously; precociousness.
precocity (n.): 1630s, from French précocité (17c.), from précoce "precicious," from Latin praecocem (nom. praecox); see precocious.
precognition (n.): "foreknowledge," mid-15c., from Late Latin praecognitionem (nom. praecognitio), noun of action from past participle stem of Latin praecognoscere "to foreknow," from prae "before" (see pre-) + cognoscere "to know" (see cognizance).
preconceive (v.): 1570s, from pre- + conceive. Related: Preconceived; preconceiving.
preconception (n.): 1620s, from pre- + conception. Related: Preconceptions.
precondition (n.): 1825, from pre- + condition (n.). As a verb from 1841.
preconscious (adj.): 1860, from pre- + conscious (adj.).
precool (v.): also pre-cool, 1904, from pre- + cool (v.). Related: Precooled; precooling.
precursor (n.): early 15c., from Middle French precurseur and directly from Latin praecursor "forerunner," agent noun from past participle stem of praecurrere, from prae "before" (see pre-) + currere "to run" (see current (adj.)). Related: Precursory.
predacious (adj.): also predaceous, 1713, from stem of predation (Latin praedari) + -acious.
predate (v.): "to seek prey," 1974, a back-formation from predator, etc. Related: Predated; predating. For the word meaning "antedate; pre-exist," see pre-date.
predation (n.): late 15c., "act of plundering or pillaging," from Latin praedationem (nominative praedatio) "a plundering, act of taking booty," from praedari "to rob, to plunder," from praeda "plunder, booty, prey" (see prey (n.)). Zoological sense recorded from 1907.
predator (n.): 1862, from Latin praedator "plunderer," from praedari "to rob" (see predation). Originally Predatores (Swainson, 1840) used of insects that ate other insects.
predatory (adj.): 1580s, "involving plundering," from Latin praedatorius "pertaining to plunder," from praedator "plunderer," from praedor "to plunder," from praeda "prey" (see prey (n.)). Of animals, from 1660s.