Rayonnant

Rayonnant is a fancy word that people use when they talk about how pretty and fancy buildings were built a long time ago in Europe.

Imagine a very special building, like a big church. It is so big that it needs lots and lots of support to keep it standing up tall.

One of the ways people added support was by using decorations! They would put pretty curves and lines all over the building.

When people say this building is "rayonnant," it means that it has lots of decorations that make it look like it's glowing with light.

So, to sum it up: Rayonnant is a way of describing the special decorations that were put on really big buildings a long time ago in Europe. These decorations made the buildings look very pretty and fancy, like they were glowing with light.