A couple of days ago, I tried to answer a journalist's questions about nonplussed ("Nonplussed about nonplussed", 8/6/2008). I wasn't entirely satisfied with one of my answers, and so I've tried again today.
The question was
Q: Is it possible for a word to become so commonly misused that the new (wrong) definition becomes acceptable? Has any word like this ever had its new meaning included in a dictionary?
The answer, of course, is that every word in every language has been through many cycles of "misuse" becoming "acceptable" — this process is otherwise known as language change. (Some English words have not changed a great deal in the few centuries since reliable dictionaries for English have existed — but that's another matter.) As examples, I cited the journey of silly from "happy, blissful" to "foolish, simple", by way of "pious", "innocent", "helpless", and "insignificant". I also mentioned dirt's shift from excrement to mere soil.
But in the comments, Ann objected:
I'm not sure that "silly" is really a good example of the process that might be happening with "nonplussed." In the former, each subsequent definition represents a slight shading of meaning, an expansion from meaning A to meaning B to meaning C, etc. But with "nonplussed," it seems as though people simply don't know what it means and are getting it wrong, probably from the negation you noted.
I worried about this myself in writing that post. Of course, it's usual to subdivide modes of semantic change more finely than just "an expansion from meaning A to meaning B to meaning C". Thus Leonard Bloomfield's 1933 taxonomy used the categories of narrowing, widening, metaphor, metonymy, synecdoche, hypobole, litotes, degeneration, and elevation. And some of these are not at all a "slight shading" of change, but rather a quantum leap.
But it's true, the use of nonplussed to mean "unfazed" doesn't really seem to fall into any Bloomfield's categories as I understand them. And a quick glance at Andreas Blank's 1998 taxonomy — and the other taxonomies listed in the Wikipedia article — also fails to find any category that exactly fits. (Though maybe "cohyponymic transfer" is relevant, and perhaps for that matter "metonymy" if you interpret it so loosely as to mean reference to any associated concept.)
In contrast, the standard examples of words whose usage has shifted so far that they turn almost into their own opposites, and perhaps back again — peruse, fulsome, moot, nice — fit one or another of the standard categories of semantic change pretty well. So what should we do with cases like nonplussed"? Here it seems that people are using a word W that means X to mean Y instead, where the only real connection between Y and X is that both are in the same general area of abstract concepts? (At least in these cases, there are also some things about the form of W that promote the mistake, and this seems likely to be true in general, if only for functional reasons.)
There are many examples of historical change where people in some sense "got it wrong" as they did with nonplussed, as opposed to just promoting a connotation or a figurative usage to become part of the core meaning, or regularizing irony, or bleaching out some aspect of the core meaning to allow wider usage. But the obvious examples in the textbooks are folk etymologies (i.e. triumphant eggcorns) like hangnail, or morphological analogies as in the historical developments among abidden, aboden, abode and abided.
So am I missing something in the standard taxonomies of semantic change, or do we need a new category for examples like nonplussed ?
(I don't mean to suggest that the phenomenon is new, just that the standard taxonomies don't seem to have a place for it, unless I've missed something. Which I might well have done, since this is not an area that I know very well.)