Up until at least the 1993 edition, the Associated Press Stylebook called for the word teenager to be spelled teen-ager -- with a hyphen. I'm sure this was one of the most ignored rules in AP history, but it's interesting to note that some authorities were still hanging onto this compound as a two-word structure long past the 1950s, when teen culture made its first big impact and made both the hyphen and Beethoven roll over.
