equity

First recorded in 1275–1325; Middle English equite, equitee, equyte, from Old French equité, from Latin aequitāt-, stem of aequitās “evenness, smoothness, fairness”; see equi-, -ty²

Equity is a great example of a word that started out with a general sense that developed more specific senses over time, while still retaining the original meaning. The very first meanings of equity in English were a direct translation from the original Old French equité, a word whose Latin root means “even,” “just,” and “equal.”
It was not until the late 16th century that a new meaning—one that placed equity in the arena of law—emerged. Perhaps because many of the usages of equity involved legal disputes over rights and claims of ownership, by the turn of the 20th century, the word started being used in another sector: finance. It was at this point that terms such as “home equity” and “equity loan” became common finance terms. At the same time, equity started popping up in terms of stock and asset ownership.
In 1913, a small group of actors founded the labor union, Actors’ Equity Association—proof that the original sense of equity was still very much alive. This union, often referred to simply as “Equity” (with a capital E), fights for the rights of actors in the spirit of equity’s Latin roots.