Editing Abscissa and ordinate (section)

{{short description|Horizontal and vertical axes/coordinate numbers of a 2D coordinate system or graph}}
{{Citations needed|date=May 2024}}
[[File:Cartesian-coordinate-system.svg|thumb|right|250px|Cartesian plane with marked points (signed ordered pairs of coordinates). For any point, the ''abscissa'' is the first value (x coordinate), and the ''ordinate'' is the second value (y coordinate).]]
In [[mathematics]], the '''abscissa''' ({{IPAc-en|æ|b|ˈ|s|ɪ|s|.|ə}}; plural ''abscissae'' or ''abscissas'') and the '''ordinate''' are respectively the first and second [[coordinate]] of a [[Point (geometry)|point]] in a [[Cartesian coordinate system]]:<ref name="WolframAlpha" /><ref>{{Cite web |last=Hedegaard |first=Rasmus |last2=Weisstein |first2=Eric W. |title=Ordinate |url=https://mathworld.wolfram.com/Ordinate.html |access-date=14 July 2013 |website=[[MathWorld]] |language=en}}</ref>
: '''abscissa''' <math>\equiv x</math>-axis (horizontal) coordinate
: '''ordinate''' <math>\equiv y</math>-axis (vertical) coordinate

Together they form an [[ordered pair]] which defines the location of a point in two-dimensional [[rectangular coordinate system|rectangular space]].

More technically, the abscissa of a point is the signed measure of its projection on the primary axis. Its [[absolute value]] is the distance between the projection and the [[Origin (mathematics)|origin]] of the axis, and its [[Sign (mathematics)|sign]] is given by the location on the projection relative to the origin (before: negative; after: positive). Similarly, the ordinate of a point is the signed measure of its projection on the secondary axis. [[Cartesian_coordinate_system|In three dimensions]], the third direction is sometimes referred to as the ''[[wiktionary:applicate#Noun|applicate]]''.<ref>{{Cite web |title=Cartesian coordinates |url=https://planetmath.org/cartesiancoordinates |access-date=2025-04-02 |website=[[PlanetMath]] |archive-url=https://web.archive.org/web/20250221122412/https://planetmath.org/cartesiancoordinates |archive-date=2025-02-21 |url-status=live |quote='applicate' is rare in English, but its [equivalents]<!-- fixing typo in source --> in continental European, [such as]<!-- clarifying wording of source --> 'die Applikate' in German and 'aplikaat' in Estonian, are more known.}}</ref>