In general 3D printing is called 3D printing. But there are many other names or acronyms used for this technology.
So far I have seen:
- Additive Manufacturing (AM) — as opposite to subtractive manufacturing (CNC and others)
- Additive Fabrication (AF)
- Rapid Prototyping (RP) — old term when the technology was mostly used to make.. well.. prototypes
- Solid Freeform Fabrication (SFF)
- Additive Layer Manufacturing (ALM)
I am not sure who thought of the term 3D printing. Personally I favor 3D printing simply because most people immediately have some sense on what it means.