Screen-door transparency
Faking translucency by drawing only some of the pixels, so the background shows through the gaps like through an insect screen.
Proper alpha blending needs translucent surfaces sorted and drawn back to front, which is expensive and sometimes impossible. The alternative is to make every pixel either fully there or fully gone, discarding a share of them in a fixed pattern — usually a Bayer matrix borrowed from dithering. The depth buffer works as normal and nothing needs sorting.
The Sega Saturn is the textbook case: its two graphics chips couldn't reliably blend polygons against the background layers, so shadows and water got a visible checkerboard mesh that a CRT smeared into something almost acceptable. Today the same trick handles crossfades between LOD levels and makes characters fade out when they block the camera. With TAA on top, the pattern blurs away and is barely visible.