Dear Mr Foster

Thank you for your message. I am sorry, but I am not sure which of our dictionaries you have been reading. This is the mailbox of the full Oxford English Dictionary Online, which is a mixture of old and new text. Four times a year we add both revised and new entries to the text, and you can read about the most recent additions at http://www.oed.com. The public pages are open to all, though the rest of the text is for subscribers; all the English public libraries subscribe, and many allow their readers remote access. I can assure you that this dictionary has contained an entry for Teflon since 1986, and for Muggle in the Harry Potter sense since March 2003 (there are three other entries for older uses of the word).

The phrase thank you is properly written as two words. If it is used as a modifier, it should be hyphenated: a thank-you letter. We cannot recommend non-standard forms in our dictionaries and usage guides.

Margot Charlton

Oxford English Dictionary