cline (n.)

A term used in HALLIDAYAN LINGUISTICS to refer to a continuum of potentially infinite gradation, e.g. the range of possible contrasts between FALLING and RISING PITCH levels, or the degrees of contrast capable of being drawn along a time scale. Since its original use in SCALE-AND-CATEGORY GRAMMAR, the term has come to be used in other fields than linguistics, often unnecessarily, as a synonym for ‘continuum’.