Appendix:Sherlock Holmes concordance/X


 * x 1

Oddly, the only word used in the entire Canon that begins with 'x' is x itself.

From The Greek Interpreter.

 Mycroft picked up the Daily News, which was lying on the side-table.

"'Anybody supplying any information to the whereabouts of a Greek gentleman named Paul Kratides, from Athens, who is unable to speak English, will be rewarded. A similar reward paid to any one giving information about a Greek lady whose first name is Sophy.  X 2473.'  That was in all the dailies.  No answer." 

I suppose the X 2473 is an anonomous reply service either provided by the newspaper or well-known enough at the time to be understood in context.