Without wishing to be
pedantic... oh, all right, maybe I do, but anyway, I think it's worth mentioning that
TARDIS actually stands for Time And relative Dimen
sion In Space (
singular dimension).
In the original episode, 'An Unearthly Child', The Doctor's granddaughter Sarah tells someone "it stands for Time And Relative Dimension In Space". Okay, so ever since then it's been more than one Dimensions, but that first instance is canonical. Sorry, guys.
The TARDIS was notable for being bigger on the inside than on the outside.
wertperch points out that
http://www.bbc.co.uk/cult/doctorwho/tardiscam/intro.shtml states: "
TARDIS, of course, stands for Time And Relative Dimensions In Space. Or Time and Relative Dimension in Space, if you're a
purist." Vindicated at last.