Farewell, etui: The changing language of crosswords. The vocabulary of crosswords is like the dialect of an alternate and highly specific universe, populated by Ednas and Enids and Ians; where the food is Oreos and oleo and the drinks ales and tea. It embraces particular bits of French (ami, ete), Latin (esse, ave), Spanish (este, oro), and even a little Hindi (Sri). It wields an epee with elan; is on familiar terms with tsars and emirs; enjoys music, especially the oboe and altos, and likes to travel: Iran, Oslo, Reno, Etna. And it's interested in science, exploring ions and the atom, as well as the erne and the orca.
Ben Zimmer at Visual Thesaurus has a follow-up to the column above, including a list of words that are often used in crosswords but rarely in everyday language.