Definitions for "Rayonnant"
Phase of French architecture corresponding to early bar-tracery. (Martindale, Andrew. Gothic Art, 269)
the development of French Gothic which produced multiple light windows with geometric tracery
Or "radiant" style of Gothic architecture, dominated the second half of the 13th century and was associated with the royal Paris court of Louis IX. Fundamental features of rayonnant style include bar tracery and stained glass.