What is "diastyle"

Intercolumniation \In`ter*co*lum`ni*a"tion\, n. (Arch.) The clear space between two columns, measured at the bottom of their shafts.
--Gwilt.

Note: It is customary to measure the intercolumniation in terms of the diameter of the shaft, taken also at the bottom. Different words, derived from the Greek, are in use to denote certain common proportions. They are: Pycnostyle, when the intercolumniation is of one and a half diameters; Systyle, of two diameters; Eustyle, of two and a quarter diameters; Diastyle, of three diameters; Ar[ae]ostyle, of four or more, and so great that a wooden architrave has to be used instead of stone; Ar[ae]osystyle, when the intercolumniations are alternately systyle and ar[ae]ostyle.

Diastyle \Di"a*style\, n. [L. diastylus, Gr. ?; dia` through, asunder + ? pillar, column: cf. F. diastyle.] (Arch.) See under Intercolumniation. [1913 Webster] ||

n. (context architecture English) An intercolumnation of three column diameters.