What is the term for a carved design that projects slightly from a flat or curved surface?

The term for a carved design that projects slightly from a flat or curved surface is "relief." In relief sculpture, the design is not fully three-dimensional; instead, it stands out from the background in a way that gives it depth without being entirely detached from the surface.

A cameo is a specific type of relief that usually features a profile portrait, often made from materials like shell or stone, where the background is carved away to create contrast with the raised image. While cameos do fit the definition of relief, they represent a more specialized aspect of it.

Engraving refers to the process of incising a design onto a hard surface, typically creating a level surface rather than a raised projection.

Inlay involves setting a material into another, creating a contrast between surfaces and is used for decorative purposes, but does not inherently involve a projecting design.

Thus, relief is the broader term that accurately encompasses any carving that stands out from a surface, whether flat or curved.