Is "smart" too broad a term?

Last night I watched Rain Man for the first time (yeah, I know, I’m late to the party). That and this question made me think. Is “smart” a blanket term? Subjective?

In the movie, Raymond was brilliant with numbers. But he had no concept of pretty much anything else. If you said he was stupid, that would be wrong, because he’s brilliant with numbers. If you said he was smart, that’s also wrong, because he’s only smart about one thing.

Same with the dog question. The dog might not be able to get out of a blanket quickly. Or he may just like to be under it. Or maybe he’s playing. But he can get to that treat under the bucket in half a second after he was shown where it was.

What makes one smart, and who decides what the criteria are?