Abscissa
High School
Definition
The perpendicular distance of a point in an ordered pair from the vertical axis as an absolute value. It is usually the horizontal coordinate when you are working with a point on a Cartesian plane—also known as the x-coordinate. When you have an ordered pair, you have two terms: the abscissa (usually the x coordinate in the pair), and the ordinate (usually the vertical y coordinate).
Worked examples
\((5, -3)\)
The abscissa is \(5\), the horizontal distance from the y-axis; the ordinate is \(-3\).
\((-2, 7)\)
The abscissa is \(-2\); it's negative because the point lies left of the y-axis.
Common mistakes
- In \((3, 8)\), the abscissa is \(8\) → In \((3, 8)\), the abscissa is \(3\) The abscissa is always the first coordinate (x), not the second.
- The abscissa of \((-4, 2)\) is \(4\) because distance is positive → The abscissa of \((-4, 2)\) is \(-4\) Abscissa keeps its sign; it's the coordinate value itself, not absolute distance.
- Abscissa and x-coordinate are different things → Abscissa is another name for the x-coordinate They are synonyms; abscissa always refers to the horizontal coordinate.
Where you'll use it next
You'll use abscissa when describing function domains, graphing relations, working with parametric equations, and analyzing data in coordinate systems throughout algebra, precalculus, and calculus.
Found in 1 StudyPug lesson
Mastering the Cartesian Plane: A Complete Guide
7th Grade7thGrade 7 Math
Unlock the power of the Cartesian plane with our in-depth guide. Learn to plot points, navigate quadrants, and apply concepts to real-world problems. Perfect for students at all levels.
See also
Reviewed by Pat Cheng, M.Ed. — StudyPug Curriculum Lead · Last updated June 6, 2026