The other day in carpool he used the words rarely and occasionally interchangeably and when questioned said, "Well, they mean the same thing."
"Not quite," I replied, "Rare, when not referring to the optimal way to cook meat, is the opposite of often. So rarely quite specifically means that a phenomenon does not happen often. Occasionally means that the phenomenon happens on occasion. The occasion could be frequent, although usually not. So you are, for the most part, correct in saying they mean the same thing. But there is a subtle difference."
"How do you know so much about words?" CD asked, surprised.
"I'm a writer. I work with words for a living."
"Wait, really. I thought you were a crazy guy who just drove carpool."
"No, I've written three books, and I'm writing two more." Well technically two of them are co-authored, but still. I'm talking to an nine-year old.
"And dozens of articles!" Why I'm trying to impress him is beyond me.
"So people pay you to write?"
"Yeah, but not very much."
"So do you ever write anything cool?"