equation

Where does the word "equation" come from? It comes from Latin aequus, passing through Latin before entering English (1400s).

Equation’s story begins in Latin: aequus meant “equal, even.” Equal, even, giving rise to aequare (to make equal). Within Latin, it grew into aequatio by ancient. An equalizing, a making equal, from aequare. It reached English by 1400s as equation. Settled as the English word for a mathematical statement showing two expressions are equal. Today, equation means a mathematical statement showing that two expressions are equal.

1. Stage 1 · Latin · ancient aequus "equal, even", equal, even, giving rise to aequare (to make equal).
2. Stage 2 · Latin · ancient aequatio "an equalizing, a making equal", an equalizing, a making equal, from aequare.
3. Stage 3 · English · 1400s equation "a mathematical statement showing two expressions are equal", settled as the English word for a mathematical statement showing two expressions are equal.