Certainly chess is played widely enough that some of its specific terminology could provide acceptable words. Examples that come to mind are
castled and
castling, which are in our word list. (Not to mention
checkmate and
stalemate, both of which have been nine-letter words in previous puzzles - but these words are not good examples, since they have taken on figurative senses, and are known to people who know nothing about chess.)
However
luft is in a different category from the verb
castle, since castling is part of the rules of the game, so anyone who has ever played, or attempted to play, chess is likely to have encountered the term, whereas
luft is a term used in discussing the strategy of the game, and may be unknown to the casual player.
It seems to me that
luft is too rare for our purposes. I can't see it in any general dictionary. Some of the online chess glossaries include it, but others don't. It does not appear at all in the hundreds of millions of words sampled in COCA and the BNC. A usage example I found in a
newspaper chess column had the word in quotes - "White therefore needs to make 'luft' for his king ...", implying, I suspect, that the term is not quite standard chess terminology.
So I'm not inclined to make space for
luft.
