Noun

(uncountable)   The act of regulating or the condition of being regulated.

(countable)   A law or administrative rule, issued by an organization, used to guide or prescribe the conduct of members of that organization.

*{{quote-magazine, date=2013-05-17

, author=George Monbiot, authorlink=George Monbiot , title=Money just makes the rich suffer , volume=188, issue=23, page=19 , magazine=(The Guardian Weekly) citation , passage=In order to grant the rich these pleasures, the social contract is reconfigured. […]  The public realm is privatised, the regulations restraining the ultra-wealthy and the companies they control are abandoned, and Edwardian levels of inequality are almost fetishised.}}

* Army regulations state a soldier AWOL over 30 days is a deserter.

(European Union law) A form of legislative act which is self-effecting, and requires no further intervention by the Member States to become law.

(lb) Mechanism controlling DNA transcription.

(lb) Physiological process which consists in maintaining homoeostasis.

Noun

(en noun)

(mathematics, physics) A variable kept constant during an experiment, calculation or similar.

(programming) An input variable of a procedure definition, that gets an actual value (argument) at execution time (formal parameter) .

Roughly, a tuple of arguments could be thought of as a vector, whereas a tuple of parameters''' could be thought of as a covector (i.e., linear functional). When a function is called, a '''parameter tuple becomes "bound" to an argument tuple, allowing the function instance itself to be computed to yield a return value. This would be roughly analogous to applying a covector to a vector (by taking their dot product (or, rather, matrix-product of row vector and column vector)) to obtain a scalar.

(programming) An actual value given to such a formal parameter (argument or actual parameter) .

A characteristic or feature that distinguishes something from others.

(geometry) In the ellipse and hyperbola, a third proportional to any diameter and its conjugate, or in the parabola, to any abscissa and the corresponding ordinate.

The parameter of the principal axis of a conic section is called the latus rectum.

(crystallography) The ratio of the three crystallographic axes which determines the position of any plane.

(crystallography) The fundamental axial ratio for a given species.