comprehension as applied to a term, the set of attributes implied by a term. The comprehension of ‘square’, e.g., includes being four-sided, having equal sides, and being a plane figure, among other attributes. The comprehension of a term is contrasted with its extension, which is the set of individuals to which the term applies. The distinction between the extension and the comprehension of a term was introduced in the Port-Royal Logic by Arnauld and Pierre Nicole in 1662. Current practice is to use the expression ‘intension’ rather than ‘comprehension’. Both expressions, however, are inherently somewhat vague. See also AXIOM OF COMPREHENSIO. V.K.