My in-laws are not big fans of the Scrabble Dictionary, with its massive list of arcane words. If the probability that a word comes up in everyday conversation approaches zero (i.e. zoeal), or if it is a shortened form of another word (i.e. za), or if it is a blatant perversion of a well-known word (i.e. luv), then it probably won’t be popular with them.

Consequently, they would like this, from Andrew Gelman. He decries the acceptability of foreign words like qat and xu, but as a commenter points out, where do you draw this line, since many English words are borrowed from other languages?

I think the Scrabble Dictionary gets a bad rap. It is simply reflective of the words which are considered, by one dictionary or another, to be valid English words. To craft an alternate list of admissible words would be hugely confusing, unless clear guidelines could be established which would easily distinguish “Scrabble words” from others (akin to the rule that no proper nouns are permitted).

I do think that in a “friendly” game, a reasonable rule would be that a player should be able to honestly define any word that is laid. Or, alternatively, decide on a dictionary and allow people to look up their words before they play them. The problem with the latter rule is that it renders infeasible the concept of the Challenge, which is a really interesting part of the game.