Barbara McNichol forwarded me a question about the expression one-off as used to mean “one of a kind.”
I really thought the correct slang was ‘one OF’, not OFF, as in short for ‘one of a kind’. So if that’s true, how did ‘one of’ morph into ‘one off’? Or is it simply that people are spelling it incorrectly?
Although the definition of one-off contains the word of, the expression has always been one-off.
The expression is fairly new in American usage. It began as a British expression and derives from manufacturing jargon. Its first recorded date of use is 1934.
As a noun, one-off is defined in the OED as
A manufactured product made as the only one of its kind; a prototype; (more generally) something not repeated.
One-off can also be used as an adjective:
Made or done as the only one of its kind; unique, not repeated.
The popularity of the expression in headlines on the web will ensure that its use will no longer be confined to speakers of British English:
Vespa builds a one-off, four seater ‘Stretch Scooter’
Exclusive one-off London Bestival Party for 2010
Was Nigerian bomber a one-off?
Darling announces one-off shock tax to ‘break bonus culture’
The Top 10 Weirdest One-off Characters On Lost
That is all true. However, I barely recall reading “one-off” more recently. I don’t remember the book, but when I saw ‘one-off’ I thought that they must mean ‘one-of-a-kind’. So that was its first appearance in my long, well-read life. I cannot find it in the first five Harry Potter books. They were responsible for our now referring to redheads as ‘gingers’. American usage of one-off is within the past 25 years. I believe it came from one popular literary source.