In the novel I am currently reading I came across the phrase "Let's have the gen". I have known this word "gen", meaning information, since I was a lad but had never paused to think about how it came to mean that. I assumed it was a leftover from World War II "military speak" since it seemed that it was primarily used by men who had been through the war. Its appearance in the novel, especially since I was reading a translation from Swedish, made me look it up. Disappointingly, the only explanation I have found is that it is short for general information. But it seems I was right about WWII and it is chiefly of British usage.
Have you any neglected words to bring into the limelight?