The term is broader and more useful than "AI content", because it covers the middle ground where most professional work actually sits: a real shoot with a generated environment, a real voice with a generated read, a real product with a generated set.
That middle ground is also where the disclosure question gets interesting, and where a studio earns its fee. The skill is not generating. It is knowing which parts of a piece should be synthetic and which absolutely should not.
What counts as synthetic media?
Anything generated or materially altered by a model, including a real photograph with a generated background, or a real recording with a cloned voice.
Is synthetic media the same as AI-generated content?
Broadly, though synthetic media is the more precise term because it includes hybrid work where only part of the asset is generated.