aequatio

Aequatio is a Latin noun meaning the act or result of making equal, or the state of balance and equality. It derives from aequus, meaning equal or level, with the suffix -atio. The term is historically significant as the source of the English word equation and related derivatives.

In classical Latin, aequatio served as a technical term in mathematics and related disciplines. It denoted the relationship of equality between two expressions or quantities, effectively an equation. The term also appeared in geometric and algebraic contexts, where the emphasis was on balancing sides or terms to establish equality. In scholastic and early modern Latin texts, aequatio extended to discussions of proportion and the equating of different quantities within problems.

Beyond mathematics, aequatio appears in philosophy, theology, and rhetoric with broader senses of balance and correspondence. It can refer to harmonizing opposing factors within a philosophical argument, or to the symmetry and parallelism sought in rhetorical style, where parts of a sentence or argument are made to reflect a commensurate structure.

Today the word is largely of historical or linguistic interest. In modern mathematics and science, the concept is expressed with the standard term equation in vernacular languages, derived ultimately from aequatio. The related noun aequitas remains common for notions of justice and fairness, while aequatio is typically reserved for the sense of balance or equality in older Latin usage.