Sometimes a word slips into our language unnoticed. Before we know it, that word is everywhere.
That's how listener John Van Deusen feels about "one-off."
He says, "I thought I was paying attention, but I don't recall it beginning, and now it's everywhere -- definitely not a one-off usage."
Words can be sneaky, especially when they come in from a language close to our own.
Similar to calling a redheaded person a "ginger," calling something that only happens once a "one-off" is a British import.
There's a theory that it's a mistake, based off "one of a kind," and that the "one of" became "one off." That's not true. "One-off" comes from manufacturing. It refers to the number of products that come from a mold or pattern.
If something is a "one-off," it's the prototype, there's only one, but you could also have "two hundred-off." The Oxford English Dictionary cites this example from 1970: "Without barrier coats, mold breakdown can start after sixty units off."