1. Of a figure, having all its sides and angles equal (e.g. equilateral triangle).
2. Any one of a series of parallel chords of a conic section, in relation to the diameter that bisects each. It may be used to form an ellipse, so can be applied to the design of vaults.
"ordinate." A Dictionary of Architecture and Landscape Architecture. . Encyclopedia.com. (August 16, 2018). http://www.encyclopedia.com/education/dictionaries-thesauruses-pictures-and-press-releases/ordinate
"ordinate." A Dictionary of Architecture and Landscape Architecture. . Retrieved August 16, 2018 from Encyclopedia.com: http://www.encyclopedia.com/education/dictionaries-thesauruses-pictures-and-press-releases/ordinate