While Americans this week have marked the sad anniversary of John F. Kennedy's assassination, there is a more pleasant commemoration going on as well. On Nov. 23, 1963, the day after Kennedy died, the BBC first broadcast the science-fiction series "Doctor Who." The franchise is still going strong 50 years later. To celebrate, let's look at one of the lexical contributions of "Doctor Who": the name for the nefarious alien race, Dalek.

Daleks, lethal exterminators in tank-like robotic shells, first made their appearance in the second serial of "Doctor Who," broadcast in December 1963 and written by Terry Nation. Daleks quickly seized the British public's imagination, and Nation was often asked about the origin of the curious name. In a 1964 interview with the Daily Mirror, Nation explained that the name was inspired by an encyclopedia volume on his shelf that had "DAL - LEK" on the spine.

After the interview, Nation's encyclopedia story was dutifully picked up by other sources. In its entry for Dalek, the Oxford English Dictionary includes a 1971 citation from Radio Times: "Who are the Daleks? Dr. Who's most dangerous enemies, written into his second adventure in 1963 by Terry Nation, who named them after an encyclopaedia volume covering dal-lek."

But the explanation is decidedly fishy. As one "Doctor Who" fan (or "Whovian") points out, "Could there ever have been a time when there were fewer words/names starting with the eight letters between D and L than there were between A and C?" Besides that, it's hard to find any encyclopedia or dictionary entries for words starting with "LEK" (except for lek, an Albanian unit of currency, and lekvar, a Hungarian pastry filling).

In 1973, a decade after he dreamed up the Daleks, Nation finally came clean. He gave another interview in which he admitted that there was never any such encyclopedia:

In a desperate attempt to satisfy persistent journalists, who wanted some profound explanation for my naming the Daleks, I told them that I'd been inspired by the letters on a volume of an encyclopaedia. But . . . no encyclopaedia in print covers those letters DAL-LEK. Anyone checking the facts could have found me out . . . The name, it simply rolled off the typewriter.

The word that "rolled off the typewriter" has a somewhat harsh and mechanical sound to it — not unlike robot, a word created in 1920 by Czech science-fiction writer Karel ńĆapek, based on the Czech word robotnik meaning "slave." As it happens, dalek has a meaning in another Eastern European language: in Serbo-Croatian, dalek can mean "distant" — or even, perhaps, "alien."

According to Alwyn Turner, author of The Man Who Invented the Daleks: The Strange Worlds of Terry Nation, this was merely a coincidence. "He didn't know that at the time, as he didn't speak Serbo-Croat, of course," Turner said. "But somebody pointed it out to him and it was entirely appropriate. It was just a good combination of sounds."

It's a less enticing story to say that Nation simply came up with "a good combination of sounds" when he invented Dalek, so the encyclopedia explanation still gets trotted out (for instance in The Oxford Dictionary of Phrase and Fable). Some word-related myths are hard to exterminate, even when the coiner of the word is doing the debunking.