Monday, March 28, 2011

Word of the day: abscissa

The word of the day is abscissa:

< post-classical Latin abscissa portion of the axis of symmetry of a conic section lying between its vertex and a given chord (1673 (in Leibniz) or earlier), (in Cartesian coordinates) distance of a point from the y-axis, measured parallel to the x-axis (1692 (in Leibniz) or earlier), use as noun (short for abscissa linea a cut-off line) of feminine past participle of classical Latin abscindereabscind v. With sense 1 compare slightly earlier absciss n. Compare also earlier ordinate n.
In plural form abscissae after the Latin plural form.


Math.
 1. The portion of a conic section lying between its points of intersection with two parallel chords; (also) the portion of the axis of symmetry of a conic section lying between its vertex and a given chord. Cf. ordinate n. 1. Obs.    
2. In Cartesian coordinates: the distance of a point from the y-axis, measured parallel to the x-axis; the x-coordinate of a point. Formerly also: a straight line drawn from a given point parallel to the x-axis and meeting the y-axis. Cf. ordinate n. 2. (OED)


"FTICR mass spectra (the abscissa represents a convolution of the deuterium incorporation after 1 hr and the initial natural-abundance isotopic distribution of the fully protonated ion) following gas-phase H/D exchange for 1 hr at 2 x 10^-7 Torr D2O for the 11 - 13+ charge states of bovine ubiquitin."

 - Bogdanov and Smith, "Proteomics by FTICR mass spectrometry: top down and bottom up", Mass Spectrometry Reviews 24:168 (2005)


As far as I can tell, this word has been replaced by "x-axis" and "x-coordinate" (depending on its use).  I guess Dr. Bogdanov didn't get the memo.

No comments: