Well, this isn’t very helpful. The New Penguin English Dictionary (1986) has two definitions for aide. The first is, “an aide-de-camp.” That’s it. Just an aide-de-camp.
Aide-de-camp is the next entry in the dictionary. You’ll have to wait until I get there before I reveal what it means. I’m going to be exceptionally pissed off if the entry for aide-de-camp says merely “an aide.”
The second definition provided for aide is “an assistant.” That’s it. Just an assistant. Fortunately, everyone knows what an assistant is, don’t they? Right. Enough said.
The New Penguin dictionary says that this second definition is primarily a North American usage. When it says that, the truth is often that the usage primarily an American, as in the United States of America, not as in North America, South America, or the Americas.
However, in this case, Canada does use aide this way. So, at least in this entry, it is correct to say that it is a North American usage. Although, it would be more precise to say that the usage applies to English-speaking North America. However, one can pretty much assume the English-speaking part based on the fact that it’s an English dictionary.