A word on Japanese grammar - the na-nominal

I like the idea of putting a "word of the day" in here whenever I learn something that I find particularly interesting. Today's is going to be a special kind of word called a na-nominal, and I thought an explanation of what that means might be interesting for the half of my audience or so who isn't familiar with Japanese and informative for anyone who is interested in Japanese but hasn't learned much grammar.

One of the real mind-blowing things that really got me hooked on Japanese in the beginning is the fact that Japanese words simply can't be divided into the categories we know from English grammar. For example, every school child learns that a noun is a word representing a "person, place or thing." But Japanese nouns aren't that picky. An awful lot of them can be convinced to represent an action if you tack the auxiliary verb suru onto them. And there is an entire family of the bloody things that refuse to represent objects, and are instead used exclusively as adjectives or adverbs. These rebellious souls of the Japanese linguistic universe are called keiyoudoushi in Japanese. I learned to call them na-nominals as an undergrad, but I've discovered that there are so many nomenclatures used to describe Japanese grammar in English that in conversation I find it's easier just to learn and use the Japanese terms. I'm trying to avoid using too much Japanese vocabulary here, though, so I'll stick with na-nominal.

So how do these dastardly little rebels work? As you'd think, they mostly work like nouns - if you say "that woman is pretty", you put it together exactly as though kirei (pretty) were a noun. (Ano onna wa kirei desu.) The only time na-nominals don't look exactly like nouns is when they are used to directly modify a noun or a verb - if they're modifying a noun, you stick a na suffix onto them, and if they're modifying a verb they pick up a ni. So the "the pretty woman" is kirei na onna, and "to smile prettily" is kirei ni warau.

The reason for this historically is really interesting - the na is a shortened form of the classical Japanese copula nari. Nari following a noun means "it is [the noun]", but the copula can also go between two nouns to give you a construct meaning "the [noun A] that is [noun B]". There were evidently plenty of nouns that were only used in such a construct, which is essentially adjectival, and then the copula was shortened to the particle na.

If you've made it this far, congratulations. I promise not to post anything nearly this geeky again for at least a week.