Origin: Latin suffix -tion
Equation has 4 different meanings across 1 category:
a mathematical statement that two expressions are equal
"After solving for x, she wrote down the final equation to show that both sides were equal."
a state of being essentially equal or equivalent; equally balanced
"on a par with the best"
The act or process of equating two or more things, or the state of those things being equal (that is, identical).
"The recent merger created an equation between the rival tech giants, making their market shares effectively identical."
In plain English: An equation is a math statement that shows two expressions are equal to each other.
"The teacher asked if anyone could solve the math equation on the board."
Usage: Use "equation" to describe a mathematical statement asserting that two expressions have the same value or to refer metaphorically to balancing unrelated factors. Avoid using it when you simply mean the act of making things equal, which is better expressed as "equating."
The word equation comes from the Old French equacion, which was borrowed from the Latin aequatio meaning "an equalizing." It entered English with this original sense of making things equal.