Market is one of a cluster of words (including enterprise, value, property, and competition) which define the economic and social relations of most contemporary societies. Together, such words highlight a trading emphasis for the word commerce, rather than its more recent “interaction meaning”; and the pervasiveness of market transactions and relationships in many modern countries makes them kinds of market societies. Such societies typically express a political philosophy of market capitalism or market liberalism, tying market not only to changing meanings of liberal and liberty but also to the varied meanings of other common but complex words, including choice and trust. Market is in this way part of a configuration of socially defining words whose meanings have altered in range, implication, and connotation in step with transformations of social practices and relations. Market comes into English (and in varying forms into a number of other European languages) from post-classical Latin mercatum and is not attested before C12, having been preceded in Anglo Saxon by céap (Middle English chep and chepe), a place and time for buying and selling cattle. The word’s range of modern senses develops in overlapping processes of generalization and specialization, as well as through figurative extension. Historically and prototypically, from its earliest occurrence in C12, market carries over from Latin the meaning of “a place at which trade is conducted,” especially “a meeting or gathering together of people for the purchase and sale of provisions or livestock, publicly displayed, at a fixed time and place; the occasion or time of this.” Related market square, marketplace, and market town continue to be used; and the C20 coinage flea market describes a street market containing miscellaneous, often secondhand goods. This spatial sense is extended in contemporary, ambiguously spatial and laudatory supermarket and hypermarket. But market in this sense of physical location had perhaps its greatest importance during a period in which the economic relations associated with places for buying and selling were tightly controlled by Norman conquerors and later settlers, as part of wider systems of ownership and obligation in late feudalism and the shift into early capitalism. Market as a trading place extended in geographic scale with the historical growth of actual markets, linked (and accelerated during C18 and eC19 as a consequence of the Industrial Revolution) with changing means of transport, patterns of financing, industrialization of production, extended supply chains, and expanded areas for distribution. Increasingly, market refers to centralized markets in a market town, then more regional and national markets (often for specialized goods and services), then foreign markets and larger trade blocs such as the european market and global markets, regulated in new ways by international trade organizations such as WTO (World Trade Organization). From C15, market also denoted particular arenas of commercial activity, or classes of commodity taking over from “horse fairs” and “goose fairs” when used with a qualifier, as in corn market, poultry market, then later import/export market. Extension of this meaning allows modern education market (foreshadowed in Hazlitt’s market of learning, 1820), healthcare market, and other newly designated markets in which forms of organization and systems of value are modelled on the basis of exchange value. Independently of these politically contentious applications, market gradually encompasses not only retail sales of prototypically physical goods but Internet sales and intangibles (hence stock market and futures market), widening into what Justice Oliver Wendell Holmes Jr., building on Mill and earlier Milton, called a “marketplace of ideas.” More abstractly again, in cultural theory writers such as Pierre Bourdieu have recently applied a notion of market relations across a far wider range of symbolic fields, linked to different modalities of capital. Widening in what market can refer to is accompanied by a different process of abstraction: away from real or virtual occasions for selling toward the action or business of buying and selling. Hence, market as “a commercial transaction” is reflected in expressions such as “take to market” and “be first to market,” whether used of a farmer leading sheep along a track or a car manufacturer launching a new model at a trade show. This transaction sense paved the way for market as mechanism or process, as traced by Karl Polanyi as a market economy in The Great Transformation (1944). The more theoretical use is effectively that of the operation of supply and demand as market forces, attested from 1942 but part of a cluster reported much earlier in C20. Analysis of this process meaning of market had been central to work by political philosophers for at least two centuries, most influentially in Adam Smith’s investigation in The Wealth of Nations (1776). Market, in this sense, has remained central to traditions of economic theory, across varied models and critical positions, from lC18 to the present. One implication of a gradually lessened emphasis in market on varied social practice than on generalized principles of operation has been normative claims to efficiency. If something sells in a relevant market it may be judged to have succeeded, on the grounds that accumulated subjectively rational decisions reflect Smith’s objective “invisible hand.” From such confidence in market testing follows an increased appeal, in policy thinking, associated with market solutions. Yet once market combines favorably with “laissez-faire” and “free,” as in the compound free market (attested from mC17), tension increases regarding the degree and kinds of market regulation required to balance a competitive yet fair society: encouragement of markets and entrepreneurs opens up avenues for trade and assists innovation; yet distortion of markets (for instance, by monopolies and cartels) must be restrained by measures that depend on changing conceptualizations conveyed by other words in the same, difficult semantic cluster as market: in this case competition, freedom, fair, and trust. Almost from its earliest uses, market has also conveyed personified meanings denoting participants attending a market, people now usually described as traders or merchants and as customers or consumers. A target market of such customers can be identified by means of a market survey (attested 1914), and addressed by market segmentation and other techniques developed more recently in the field of marketing (both as a neutrally described activity, from C16, and from lC19 either favorably or pejoratively to describe strategic practices of sales promotion). Merchants or vendors themselves are market traders (whether in a street market or stock market), and marketers or marketeers; when viewed as a collective agency, they may be referred to as the market or the markets: an aggregated force serving either as metonym for actual people engaged in financial speculation, but with human skills, appetites, and fears, or as a depersonalized, abstract power beyond the individual human actors, impelling a market assumed to follow economic laws (and which, according to former UK prime minister Margaret Thatcher, could not be bucked). The market, with definite article, becomes in such circumstances a hardened abstraction, sometimes critiqued as part of wider market fundamentalism. In the context of recent global economic and political upheavals, market is an especially contested term. But the word’s polysemy and figurative application complicate the discussion and assessment of political directions and proposals. What boundaries exist, for example, as regards which social practices may be legitimately commodified and treated as markets? A market in slaves or daughters eligible for marriage, both widely reported as OED examples of market? A market in healthcare, education, or weapons; or in body parts, human stem cells, and biotech inventions? And what kinds of agency are at work in the different kinds of market: the “invisible hand” of aggregated but individually self-interest-maximizing decisions attributed to homo economicus, or more volatile social agents with—unless regulated—often little accountability as regards market outcomes?