“Greeble” refers to small, intricate details added to the surface of an object—often in visual design, 3D modeling, or special effects—to make it look more complex and visually interesting. The term is especially common in sci-fi and fantasy aesthetics, where greebles are used to give spaceships, buildings, or machinery a more detailed, lived-in appearance.

The concept was popularized by artists and model-makers working on Star Wars and other sci-fi films, where adding greebles to models helped create a sense of scale and realism. In digital design, greebling is a technique used in 3D modeling to add non-functional, ornamental geometry to an otherwise simple shape.

In short, greebles don’t serve a practical purpose but make things look more intricate and realistic.

From ChatGPT.