Parameter (noun)

1. A limit or boundary that defines the scope of a particular process or activity.
2. A variable that determines the characteristics of a system or process.
3. A quantity or value that is constant or changing in a particular equation or calculation.

Origin:

From para- (“beside”) +‎ meter, from ancient greek μέτρον (métron, “measure”).

Examples:

1. The parameter for the project's timeline is three months.
2. The temperature is a crucial parameter for the experiment.
3. The formula requires several parameters to be inputted.