profectus

Profit comes from the Old French profit, from the Latin prōfectus (advance, progress, success), from prōficere (to make progress, to advance — from prō, 'forward,' and facere, 'to make'). The word entered English in the thirteenth century meaning 'benefit, advantage, gain.' The financial meaning — money remaining after costs — was a narrowing. The original word meant any kind of forward progress.

Medieval Christianity had a complicated relationship with profit. The just-price doctrine, articulated by Thomas Aquinas in the thirteenth century, held that a fair price covered the cost of production plus a reasonable living for the merchant. Excessive profit was usury. The word profit existed in a moral framework that modern capitalism has largely abandoned. Making progress was good. Making too much progress was sinful.

Adam Smith's The Wealth of Nations (1776) reframed profit as a necessary incentive. Profit was the reward for risk and the signal that guided investment. The moral suspicion did not disappear — it moved. Medieval theologians worried about usury. Modern critics worry about profiteering, war profiting, and excess profits. The word still carries a charge.

In modern business, profit has been subdivided into gross profit, operating profit, net profit, and EBITDA (earnings before interest, taxes, depreciation, and amortization). Each measures a different kind of advance. But the Latin root still applies: profit is forward motion. Revenue minus costs. What is left after everything is paid. The advance.