I like to talk about words as a bridge to cultural communication. Unfortunately, there’s some pretty basic reasons why this is hard: even if I talk about an adjective, beginners in Japanese will want to, you know, use them. And that can be tricky at first.
Japanese adjectives come in two basic forms. Formally, we call these i adjectives and na adjectives. This is simply because of how they “end”. Two examples will suffice.
akai duressu : A red dress. (Dress is a loan word; akai = “red” as adjective)
kirei na duressu : A pretty dress. (kirei = “pretty”)
So, even though kirei ends with an “i”, it is a na adjective because we don’t use it as an adjective without adding a “na” between it and the verb.
Now, by this point you may ask, okay, how would we use these in a way that isn’t as an adjective? They’re adjectives!! But there is a way.
duressu wa aka desu.
duressu wa kirei desu.
The bolded words are nouns. If the dress is X, that X is a noun, in terms of grammar.
Now, just so you understand, this isn’t “akai as a noun” per se; it is aka, the noun for “red”. We might as well treat it as a separate word altogether; the noun and the adjective versions function completely separately.
As for kirei, yes, that’s simply kirei as a noun, with the na part dropped.
By no means do all i adjectives have a pure noun alternative form like aka. In fact, the case of aka is relatively rare. I just wanted beginners to see this up front so they understand that not all i adjectives can be beaten into line to play this role. That results in using unnatural Japanese (not on purpose, but still).
Let’s see a few examples.
ano hako wa omoi desu yo. (That box is heavy!)
kono kuruma wa chotto hiroi ne. (This car is a little wide huh.)
kyou no tenki wa kitsui desu. (The weather today is stifling.) (I suppose there are other readings but this one will do. It’s used for “intense” weather; muggy, stifling, overbearing, things like that.)
Anyway, these are all i adjectives in this case:
omoi hako (heavy box)
hiroi kuruma (wide car)
kitsui tenki (stifling weather)
So fitting this into the vocabulary you’re using mainly requires knowing what you’re dealing with.
The Two Common Exceptions
There are two common exceptions: big and small.
chiisai (small) and ookii (big) are the two most common exceptions.
chiisa na kuruma
kuruma ga chiisai
ooki na kuruma
kuruma ga ookii
It’s not hard once it’s pointed out, and you get the hang of it, but the fact it violates what seems like a firm rule will throw beginners off.
Why I Covered This
Anyone can go to a flash card site and start memorizing vocabulary in abstract. It’s quite possible many of you who read this blog actually do this, or aspire to doing it at some point.
Learning a word in abstract, with no idea how that word is actually used, is a problem that comes up a lot in language learning. With nouns, there isn’t a problem; you learn it, and that’s it. Adjectives, well, you see above how it is. It doesn’t get much more complicated than this, but until it’s been covered, people are in the dark. I wanted to do something about that.
Bonus: Why Are They na Adjectives, Anyway?
It’s hard to convey without kanji.
kirei na is 奇麗な. akai is 赤い. (If you can’t see kanji, don’t worry about it.) There are two kanji for kirei and one kanji, plus an i ending, for akai. Typically, this means kirei is an imported word, in some sense, and akai is a native Japanese word for red. As for kirei, the na acts as a kind of verbal spacer indicating that the imported word is being pressed into service as an adjective. – J