This page records what I have been able to learn about the origins of some of the terms we use in international economics. If I attribute a concept or a term naming it to a particular author, that means I have personally checked the source and seen it used there in the way that I describe. However, if I say or imply that this was the first use of a concept or term, I obviously cannot always know that for certain. If you know of prior uses that should be mentioned, please let me know, preferably by e-mail to alandear@umich.edu.
CES Function
Arrow et al. (1961, pp. 225-6) described their empirical motivation to "derive a mathematical function having the properties of (i) homogeneity, (ii) constant elasticity between capital and labor, and (iii) the possibility of different elasticities for different industries." They named it the CES function and estimated it across industries and countries.
Comparative advantage
Ruffin (2002) credits the concept of comparative advantage and the Law of Comparative Advantage to Ricardo (1951-1973), in a discovery that Ruffin dates to early October 1816. The Law was developed in Ricardo's celebrated chapter on foreign trade, while the term "comparative advantage" seems to have first appeared in a later chapter (Ricardo (1951-1973), Vol I, p. 263). In crediting Ricardo, Ruffin disagrees with Chipman (1965) who credits Torrens (1815). From what I see in this debate, Torrens deserves credit for first stating the possibility that a country will import a good in which it has an absolute advantage, even though he seems not to have recognized its importance, and he certainly did not work out the full conditions needed for this to happen, as Ricardo did.
Continuum of goods
The first to model trade with a continuum of goods were Dornbusch, Fischer, and Samuelson (1977), who also use that term in their title. They cite an unpublished paper by Charles Wilson, also dated 1977, that further explores their model, but in the published version of that paper, Wilson (1980), he credits them with having suggested this modification of traditional trade theory.
Currency area
Mundell (1961, p. 657) spoke of "...defining a currency area as a domain within which exchange rates are fixed...". Perhaps because the exchange rates among separate national currencies are seldom if ever truly fixed, the term has come to mean a group of countries that share a common currency. Mundell also coined the term "optimum currency area" which is now more commonly expressed as optimal currency area.
Diversification cone
Dixit and Norman (1980, p. 52) attribute this to Lerner (1952) and McKenzie (1955). I see nothing in Lerner to justify this. McKenzie, however, makes considerable use of the concept in the form of a set of factor endowments within which factor price equalization occurs, though he does not give it a name. Since he projects factor requirements and factor endowments onto a simplex, his set appears as a triangle, though a cone is implicit. I do not yet know who may have preceded Dixit and Norman in using this term.
DUP Activity
Bhagwati (1982) introduced this acronym for Directly Unproductive Profit-seeking Activity. After listing a variety of activities that fit this description, including rent seeking, revenue seeking, and others, he said (p. 990), "Thus, these are aptly christened DUP activities."
Edgeworth-Bowley Box
The origins of this are examined by Tarascio (1972). The Edgeworth-Bowley Box diagram got its name when Bowley (1924) drew a box around a rotated version of an indifference curve diagram of Edgeworth (1881). However, Bowley did not claim originality, and Pareto (1906) had actually been the first to draw and use the actual box diagram.
Fragmentation
Used to mean a splitting up of production processes, the term fragmentation was first introduced by Jones and Kierzkowski (1990), who start their analysis by noting (p. 31) that increasing returns and specialization encourage a growing firm to "switch to a production process with fragmented production blocks connected by service links.... Such fragmentation spills over to international markets." (Italics in original.) Many other terms have been used with the same, or related, meanings, as listed here, but "fragmentation" seems to have caught on most widely.
Immiserizing growth
The term "immiserizing growth" was used by Bhagwati (1958) and it seems unlikely that anyone used it before him, since he seems to have coined the word "immiserizing." As for the concept, Bhagwati credits Johnson (1953, 1955) with identifying a form of immiserizing growth and also with working out the conditions for Bhagwati's form of it in an unpublished note. Long before both of them, Edgeworth (1894, p. 39-40) had shown, though only by example, that increased production of exports could so reduce their relative price that the country loses or, as Edgeworth put it, is "damnified by the improvement." He in turn credits Mill (1821) with noting the possible worsening of the terms of trade, though Mill apparently incorrectly equated this worsening with a necessary decline in welfare. (I have not read Mill and am taking Edgeworth's word for this.)
Law of Comparative Advantage
See comparative advantage.
Lerner Diagram
The Lerner Diagram was first drawn by Lerner in an unpublished seminar paper in 1933. He used unit-value isoquants together with unit isocost lines to show the relationship between goods prices and factor prices in the HO Model. That paper was reproduced, "as it was originally written" according to the journal editor, as Lerner (1952). I don't know who first called it the Lerner Diagram, although Findlay and Grubert (1959) made extensive use of the diagram, attributing it to Lerner.

Some (including myself, until I learned better) have called it the Lerner-Pearce Diagram, giving credit also to Pearce (1952). In fact, although Pearce in this article was debating Lerner regarding the likelihood of factor price equalization, he used unit isoquants, not unit-value isoquants, for the purpose. Since these do not align in equilibrium with a single unit isocost line, they cannot be used in the same way, and they do not achieve the essential simplicity of Lerner's construction.

Rent seeking
Rent seeking was introduced to the trade literature by Krueger (1974), who defined it generally but applied it to quantitative restrictions on trade. She noted (p. 291) that government restrictions on economic activity "give rise to rents..., and people often compete for the rents." She called this competition rent seeking, a term that she apparently coined and that has caught on hugely.