I'm probably the only person at this site who'd get a kick out of this, but here goes, just in case:
Apparently the Oxford English Dictionary has an entry in it for TARDIS (spelt out of acronym or Tardis). It is used as an allusion to something bigger on the inside than on the out.
As a "Doctor Who" fan, this tickles me to no end. Forget Merriam-Webster; it's the Oxford English Dictionary for me from now on!
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Source:
http://www.gallifreyone.com/news.shtml#newsitemEpkVZklVkFgEFyPRkY.
Note - this is a small article among many, plus the page gets up dated almost daily, so you might have to do some wading to check it out.
Assuming you'd want to, of course