What does abscissae mean?
Abscissae is the plural of abscissa, a term from analytic geometry denoting the horizontal coordinates of points in a Cartesian plane. Each abscissa measures how far a point lies from the vertical axis, conventionally written as the x-value in an ordered pair. The word belongs firmly to mathematical and scientific writing: textbooks, research papers, and lectures use it when describing graphs, curves, and plotted data, often paired with its counterpart 'ordinates', which denote the vertical y-values. Because most speakers simply say 'x-coordinates', encountering 'abscissae' typically signals a formal or academic context. The term derives from Latin abscindere, meaning 'to cut off', reflecting the way a coordinate cuts the horizontal axis at a specific point. For anyone reading mathematics, physics, or economics at more than a casual level, recognising abscissae makes graphical descriptions easier to follow.
nounThe plural of 'abscissa': the horizontal (x-) coordinates of points in a Cartesian coordinate system, measured as distances from the vertical axis along the horizontal axis.
- The horizontal (x-) coordinates of one or more points in a Cartesian coordinate system, expressed as distances from the vertical axis.
"Plot the abscissae of the data points along the horizontal axis before drawing the curve."
"The graph plots temperature against time, with the abscissae marking hourly intervals."
"In her calculus lecture, she reminded students to label the abscissae clearly before sketching the tangent lines."
'Abscissae' is itself the standard plural of 'abscissa', following the Latin pattern. A variant plural 'abscissas' also occurs in modern usage.
"Each pair of abscissae and ordinates locates exactly one point on the plane."
Despite looking like a typo, 'abscissae' is simply the proper Latin-style plural of 'abscissa' — the x-coordinate that mathematicians have been plotting since Descartes.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of abscissae
Abscissae comes from the Latin abscissa, the feminine past participle of abscindere, meaning 'to cut off' or 'to sever' (from ab-, 'away', plus scindere, 'to cut'). The term entered mathematical English in the 17th century, during the early development of analytic geometry by figures such as Descartes and his contemporaries, describing the segment cut off on the horizontal axis by a point's perpendicular. It shares its root with other cutting-related words, including rescind, scissors, and the botanical term abscission.
Related word forms
How abscissae is actually used
A technical term used almost exclusively in mathematics, statistics, and the physical sciences. It is the plural form; the singular is 'abscissa'. In everyday speech, most people simply say 'x-coordinates', so 'abscissae' signals formal or academic register.
Easily confused with abscissae
Ordinates are the vertical (y-) coordinates of points, whereas abscissae are the horizontal (x-) coordinates.
Abscission is the botanical term for the natural shedding of leaves or fruit, while abscissae are coordinate values on a graph.