When parameters were spoken of only by mathematicians and scientists, the term caused few problems; but now that it has become widely adopted by other speakers, it is constantly confused with “perimeters.” A parameter is most commonly a numerical factor, a set of physical properties, or a characteristic of something. But the perimeter of something is its boundary. The two words shade into each other because we often speak of factors of an issue or problem being parameters, simultaneously thinking of them as limits; but this is to confuse two distinct, if related ideas. A safe rule is to avoid using “parameters” altogether unless you are confident you know what it means.