c. 1200, "price, value," from Old French cost "cost, outlay, expenditure; hardship, trouble" (12c., Modern French coût), from Vulgar Latin *costare, from Latin constare, literally "to stand at" (or with), with a wide range of figurative senses including "to cost," from an assimilated form of com "with, together" (see co-) + stare "to stand," from PIE root *sta- "to stand, make or be firm."

The idiom is the same one used in Modern English when someone says something stands at X dollars to mean it "sells for X dollars." The meaning "equivalent price given for a thing or service rendered, outlay of money" is from c. 1300. Cost of living is from 1889. To count the cost "consider beforehand the probable consequences" is attested by 1800.

In phrases such as at all costs there may be an influence or echo of obsolete cost (n.) "manner, way, course of action," from Old English cyst "choice, election, thing chosen." Compare late Old English alre coste "in any way, at all."

"be the price of," also, in a general way, "require expenditure of a specified time or labor, or at the expense of (pain, loss, etc.)," late 14c., from Old French coster (Modern French coûter) "to cost," from cost (see cost (n.)). Related: Costing.

"of great price, occasioning great expense," late 14c., from cost (n.) + -ly (1). Earlier formation with the same sense were costful (mid-13c.), costious (mid-14c.). Related: Costliness.

*stā-, Proto-Indo-European root meaning "to stand, set down, make or be firm," with derivatives meaning "place or thing that is standing."

It forms all or part of: Afghanistan; Anastasia; apostasy; apostate; armistice; arrest; assist; astatic; astatine; Baluchistan; bedstead; circumstance; consist; constable; constant; constitute; contrast; cost; desist; destination; destine; destitute; diastase; distance; distant; ecstasy; epistasis; epistemology; establish; estaminet; estate; etagere; existence; extant; Hindustan; histidine; histo-; histogram; histology; histone; hypostasis; insist; instant; instauration; institute; interstice; isostasy; isostatic; Kazakhstan; metastasis; obstacle; obstetric; obstinate; oust; Pakistan; peristyle; persist; post (n.1) "timber set upright;" press (v.2) "force into service;" presto; prostate; prostitute; resist; rest (v.2) "to be left, remain;" restitution; restive; restore; shtetl; solstice; stable (adj.) "secure against falling;" stable (n.) "building for domestic animals;" stage; stalag; stalwart; stamen; -stan; stance; stanchion; stand; standard; stanza; stapes; starboard; stare decisis; stasis; -stat; stat; state (n.1) "circumstances, conditions;" stater; static; station; statistics; stator; statue; stature; status; statute; staunch; (adj.) "strong, substantial;" stay (v.1) "come to a halt, remain in place;" stay (n.2) "strong rope which supports a ship's mast;" stead; steed; steer (n.) "male beef cattle;" steer (v.) "guide the course of a vehicle;" stem (n.) "trunk of a plant;" stern (n.) "hind part of a ship;" stet; stoa; stoic; stool; store; stound; stow; stud (n.1) "nailhead, knob;" stud (n.2) "horse kept for breeding;" stylite; subsist; substance; substitute; substitution; superstition; system; Taurus; understand.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit tisthati "stands;" Avestan histaiti "to stand;" Persian -stan "country," literally "where one stands;" Greek histēmi "put, place, cause to stand; weigh," stasis "a standing still," statos "placed," stylos "pillar;" Latin sistere "stand still, stop, make stand, place, produce in court," status "manner, position, condition, attitude," stare "to stand," statio "station, post;" Lithuanian stojuos "I place myself," statau "I place;" Old Church Slavonic staja "place myself," stanu "position;" Gothic standan, Old English standan "to stand," stede "place;" Old Norse steði "anvil;" Old Irish sessam "the act of standing."

"to price (something) excessively high," c. 1600, from over- + price (v.). Related: Overpriced; overpricing. Middle English had overdere (adv.) "too expensively, at too great cost" (c. 1300).

"of or pertaining to King Pyrrhus of Epirus," 1885, usually in the phrase Pyrrhic victory "success obtained at too great a cost," in reference to Pyrrhus's rout of Roman armies at Asculum, in Apulia, 279 B.C.E., which came at such cost to his own troops that he was unable to follow up and attack Rome itself, and is said to have remarked, "one more such victory and we are lost." The name is Greek and means "reddish" or "red-haired," from pyrrhos "flame-colored," from pyr "fire" (from PIE root *paewr- "fire").