TARDIS Meaning: What Doctor Who's Time Machine Stands For

"Doctor Who" is a cultural phenomenon that's impacted multiple generations of viewers. It launched in 1963, and while it hasn't remained in production since then, it's come and gone through several variations with multiple actors playing the Doctor. When it launched with the serial "An Unearthly Child," William Hartnell was the Doctor. His companions were his granddaughter, Susan Foreman (Carole Ann Ford), and a pair of teachers from her school, Ian Chesterton (William Russell) and Barbara Wright (Jacqueline Hill).

In "An Unearthly Child," Ian and Barbara find the TARDIS in a yard after following Susan. Upon entering (against the Doctor's wishes), they see that it's inexplicably bigger on the inside thanks to Time Lord technology. Like anyone who winds up inside the TARDIS, which looks like a police box from the outside, the two teachers are befuddled by what they find, but Susan offers an explanation. "Well, I made up the name TARDIS from the initials: Time and Relative Dimension in Space." That single line of dialogue establishes the TARDIS as both a space and time machine capable of taking its occupants to wherever (and whenever) they want.

The TARDIS became a staple of the franchise and has been featured in every incarnation of "Doctor Who." Each time a new Doctor comes along, the TARDIS gets a makeover, as does the Doctor. In many ways, the TARDIS is a character in and of itself, and the Doctor routinely talks to it like a person. During the Matt Smith era, the TARDIS used a woman named Idris (Suranne Jones) as its host to speak directly with the Doctor in the episode "The Doctor's Wife." It remains a divisive episode, but it's a testament to how important the TARDIS is both for the Doctor and the show.

The TARDIS has become an iconic image of both "Doctor Who" and British popular culture. You can even visit a real-life, to-scale (from the outside, that is) version of the TARDIS in London (it's right outside Earl's Court tube station). Pretty much everybody in the U.K. knows what the TARDIS looks like, though its full name — Time and Relative Dimension in Space — is less well known, both in Britain and abroad.

While it's made clear early on what TARDIS stands for and who named it, the series doesn't delve too deeply into its backstory. The TARDIS is a character, but it's also a refuge, a weapon, or whatever the writers need it to be in a particular adventure or episode. It's unclear who first made the TARDIS or who gave it that rather clunky name. For the most part, the series has treated the TARDIS as a plot device more than anything else, which has worked for decades.

When needed, it carries the Doctor and his companions out of danger, or its systems can be used to analyze or produce whatever is needed at the time — there's little the Doctor has asked for that the TARDIS can't deliver. It's both a technological wonder and a living organism that's capable of interacting with humans via telepathy, making the TARDIS one of the most unique vessels in all of science fiction.