marketplace n.

early 12c., "a meeting at a fixed time for buying and selling livestock and provisions, an occasion on which goods are publicly exposed for sale and buyers assemble to purchase," from Old North French market "marketplace, trade, commerce" (Old French marchiet, Modern French marché), from Latin mercatus "trading, buying and selling; trade; market" (source of Italian mercato, Spanish mercado, Dutch markt, German Markt), from past participle of mercari "to trade, deal in, buy," from merx (genitive mercis) "wares, merchandise." This is from an Italic root *merk-, possibly from Etruscan, referring to various aspects of economics.

The god Mercurius was probably the god of exchange. According to [Walde-Hoffmann], the god's name was borrowed from Etruscan; in principle, the same is possible for the stem *merk- altogether. [de Vaan]

Meaning "public building or space where markets are held" is attested from late 13c. Meaning "a city, country or region considered as a place where things are bought or sold" is from 1610s. Sense of "sale as controlled by supply and demand" is from 1680s. Market-garden "plot of land on which vegetables are grown for market" is by 1789. Market-basket "large basket used to carry marketing" is by 1798. Market price "price a commodity will bring when sold in open market" is from mid-15c.; market value "value established or shown by sales" (1690s) is first attested in the writings of John Locke. Market economy is from 1948; market research is from 1921.

c. 1200, "space, dimensional extent, room, area," from Old French place "place, spot" (12c.) and directly from Medieval Latin placea "place, spot," from Latin platea "courtyard, open space; broad way, avenue," from Greek plateia (hodos) "broad (way)," fem. of platys "broad," from PIE root *plat- "to spread."

Replaced Old English stow and stede. From mid-13c. as "particular part of space, extent, definite location, spot, site;" from early 14c. as "position or place occupied by custom, etc.; precedence, priority in rank or dignity; social status, position on some social scale;" from late 14c. as "inhabited place, town, country," also "place on the surface of something, portion of something, part." Meaning "a situation, appointment, or employment" is by 1550s. Meaning "group of houses in a town" is from 1580s.

Also from the same Latin source are Italian piazza, Catalan plassa, Spanish plaza, Middle Dutch plaetse, Dutch plaats, German Platz, Danish plads, Norwegian plass. The word appears via the Bible in Old English (Old Northumbrian plaece, plaetse "an open place in a city"), but the modern word is a reborrowing.

Sense of "a mansion with its adjoining grounds" is from mid-14c.; that of "building or part of a building set apart for some purpose is by late 15c. (in place of worship). Meaning "a broad way, square, or open space in a city or town," often having some particular use or character (Park Place, Waverly Place,Rillington Place) is by 1690s, from a sense in French. Its wide application in English covers meanings that in French require three words: place, lieu, and endroit. Cognate Italian piazza and Spanish plaza retain more of the etymological sense.

To take place "happen, come to pass, be accomplished" (mid-15c., earlier have place, late 14c.), translates French avoir lieu. To know (one's) place "know how to behave in a manner befitting one's rank, situation, etc." is from c. 1600, from the "social status" sense; hence the figurative expression put (someone) in his or her place (1855). In in the first place, etc., it has the sense of "point or degree in order of proceeding" (1630s). Out of place "not properly adjusted or placed in relation to other things" is by 1520s. All over the place "in disorder" is attested from 1923.