Tessellation is a mosaic pattern, a design made of shapes fitted together. You could compliment your friend's newly tiled kitchen floor by saying, "What gorgeous tessellation!"
If you imagine a patchwork of tiles, or the patterns in a quilt, you're picturing one kind of tessellation. Another type is mathematical tessellation, which is closely related to the first kind — it's the geometric repetition of one shape over and over again. The Latin root word tessellatus describes something made of small stones or tiles.