“The term parameter, which originates in mathematics, has a number of specific meanings in fields such as astronomy, electricity, crystallography, and statistics.”

Perhaps because of its ring of `technical authority', it has been used more generally in recent years to refer to any factor that determines a range of variations and especially to a factor that restricts what can result from a process or policy. In this use it often comes close to meaning "a limit or boundary." Some of these new uses have a clear connection to the technical senses of the word. For example, the provisions of a zoning ordinance that limit the height or density of new construction can be reasonably likened to mathematical parameters that establish the limits of other variables. Therefore one can say : "The zoning commission announced new planning parameters for the historic district of the city". But other uses go one step further and treat parameter as a high-toned synonym for `characteristic'. There are several difficulties with the nontechnical use of the word `parameter' that may arise from its resemblance to the word `perimeter', with which it shares the sense “limit,” though the precise meanings of the two words differ markedly. This confusion probably explains the use of `parameter' in a sentence such as “U.S. forces report that the parameters of the mine area in the Gulf are fairly well established”, where the word `perimeter' would have expressed the intended sense more exactly.

Other, rarer, confusion occurs when the old English spelling of `parametre' -originating from the French word `paramètre'- is employed instead of the now utilized spelling of `parameter' by non-native English speakers using out-of-date English dictionaries.

In general use, `parameter' “refers to a distinguishing characteristic or factor, especially one that can be measured or quantified: the parameters of light are brightness and colour. It has come to be used loosely to mean a limit. This is not incorrect, but it sounds like jargon. Before using it consider whether limit; scope; boundary, or a similar word would be more suitable.” (excerpt from the online Dictionary of English)