Arbitrage
Exploiting a price difference for the same asset across two or more markets, profiting from the gap before it closes.
Origin
From the French arbitrage ("judgment"), itself from Latin arbitrari ("to give judgment"). French mathematician Mathieu de la Porte gave the term its financial meaning in his 1704 treatise La science des négociants et teneurs de livres, describing the calculation of exchange rates across markets to find the most profitable route for bills of exchange. The practice of exploiting price differences, however, dates to ancient coin and bullion trading.
Everyday Use
Buying a concert ticket at face value and reselling it on a secondary market at a markup is a basic form of arbitrage. The same logic drives currency traders, stock market algorithms, and anyone who spots a price gap between two places and bridges it for a profit.