As for who gets to decide, that's easy - it's me. (Although I'm always willing to receive advice and suggestions.)
As for the criteria used in labelling a word "common", that's probably a bit vaguer. I think on different occasions I've probably given various explanations of the "standard" or "common" word list.
I suppose what I'm really aiming for is to flag the words that most players are likely to recognise. When you look at the solution and see the last few "common" words that eluded you [I suppose we could call them "eluders"], I want you to say, "Of course, how stupid of me!", rather than, "Huh! What the dickens do those words mean?!"
Of course, the problem is that every person knows a different set of words, so there's no way a "perfect" classification of words can be achieved.
Problems are likely to be of two kinds, similar to the "Type 1" and "Type 2" errors in statistical analysis.
1. The player is desperately seeking the last common word, and suddenly thinks of, say, "nuder". She plays it, and it's accepted, but, to her disgust, it's not counted as a common word.
2. On another occasion, the player looks at the solution the next day and sees that the word she didn't find was, say, "irenic" - a word she's never heard of. And so, she's cheesed off.
If all the problems were of type 1, it would probably signify that the common word list should be expanded. If all the problems were of type 2, it would probably mean the common word list should be pruned. However, if both kinds of problem crop up fairly often, it might mean the word classification is about right. That's my theory, anyway!
My impression is that, if anything, the "common" classification currently includes a few words that possibly shouldn't be there. What does everyone else think?
Would people like the common word list to be made available in some form on the Web site? I could do that if people thought it would be useful or interesting. But I would hate to think people would be burning the midnight oil studying the list, and trying to memorise it.
With regard to the specific questions raised by 3-B, about "eluder" and "nuder", quite a large percentage of the words in our full list are inflections and derivations of other words. But often, I feel the derived words are much more rarely used than the base word. So, a word is not automatically classed as common just because it is derived from a common word.
For example, our list includes the following words derived from "abet":
- ABET
- abetment
- abettal
- ABETTED
- abetter
- ABETTING
- ABETTOR
The three words shown in lower case are classed as rare, the others as common.
The
British National Corpus contains 77 usage examples for "elude" but none for "eluder". It has 408 examples using the word "nude", but only one with "nuder":
Will Jeff Koons do for Sgarbi what he did for that other member of the Italian Parliament, the even nuder Cicciolina?�
(We still don't really know how you can be nuder - possibly the other person was only partially unclad, not truly nude at all, but the use of nuder is valid in a jocular context.)
So, I'm reasonably satisfied that these two words don't belong in the common list.
But none of the above comments should be taken to imply that I think there's nothing wrong with the existing word classification. There are thousands of words involved, and I've had to make a lot of snap judgements, so there are bound to be errors and inconsistencies. So don't hesitate to keep raising questions.