If they dont get sold?

Things that make you go hmmm....

The reason i ask is that i have just been doing some research ongay slang terms tying to find how many of the are actually in the dictionary and i figured there must be one or two (at least) new words added to the dictionary every year so, where do old unsold dictionarys go? I mean its not like you would walk into Barnes And Noble tomorrow if you wanted to buy a dictionary and ask for the 1998 copy is it?

Regards,

Lee