Because it’s been employed in so many fields—from algebra, to genetics, to aerospace, to sex and spirituality—X's many meanings make it the most mystifying letter of the alphabet.

As letters of the alphabet go, there is one that punches well above its weight. Out of a total of 308,000 entries in the Oxford English Dictionary, just 366 words begin with the letter "x", and ...

Even though x is one of the least-used letters in the English alphabet, it appears throughout American culture – from Stan Lee’s X-Men superheroes to “The X-Files” TV series. The letter x ...

Because it’s been employed in so many fields—from algebra, to genetics, to aerospace, to sex and spirituality—X's many meanings make it the most mystifying letter of the alphabet.