When is a plastic a plastic?

The original question was:

It is a very simple question with a pretty broad context. The POM Draupnir, for example, is a plastic yoyo, right? The fact that it has metal rings doesn’t disqualify it from being added to the list. ZaYoBoy didn’t ask what made any particular yoyo capable of playing at a competition level, so I didn’t think it would matter to him whether it was the fact that it was machined (instead of molded), or had metal rings, or was sprinkled with pixie dust.