1. Engaged columns, bases, pedestals, and entablature attached to an arcuated structure as in a triumphal arch, or a series of superimposed Orders and arches as in the Roman Colosseum.
2. Successive planes of diminishing concentric arches with colonnettes, as in a compound arch or a Romanesque doorway.
"arch Order." A Dictionary of Architecture and Landscape Architecture. . Encyclopedia.com. (August 21, 2018). http://www.encyclopedia.com/education/dictionaries-thesauruses-pictures-and-press-releases/arch-order
"arch Order." A Dictionary of Architecture and Landscape Architecture. . Retrieved August 21, 2018 from Encyclopedia.com: http://www.encyclopedia.com/education/dictionaries-thesauruses-pictures-and-press-releases/arch-order