When this happens in dictionaries it's called a "ghost word" and dates back to the 1800's. Here's the wikipedia page on the topic http://en.wikipedia.org/wiki/

When this happens in dictionaries it's called a "ghost word" and dates back to the 1800's. Here's the wikipedia page on the topic http://en.wikipedia.org/wiki/Ghost_word http://en.wikipedia.org/wiki/Ghost_word