Another way to say "big" in Japanese is "dekkai," as in "dekkai yatsu datta (he was huge)"
jeep
The na adjective version of ookii can only be used with abstract concepts. i.e. ookina mondai (a big problem).
deviruchi
Adjectives are seperated into 3 groups, much the same way that verbs are. these groups are い-Adjectives, な-Adjectives, and irregular Adjectives.
いーadjectives are the easiest to spot because the end with い examples おいし<font color=blue>い</font> 大き<font color=blue>い</font> 小さ<font color=blue>い</font>
な-adjectives are all adjectives that don`t end with い, they are called な- adjectives because when you attach them to nouns you insert a な at the end of the adjective. example 親切<font color=red size=1>な</font>ひと at the moment I can@t think of any other examples but trust me there are more than a few な adjectives. if you see two kanji together then chances are it is a な adjective.
the final group is the Irregulare adjectives. As I`m sure you have guessed they get their name because they don`t follow the rules of the other two groups. Irregulare adjectives are adjectives that end in い but when attached to a noun follow the rules of the な adjectives. The best example of this is きれ<font color=blue>い</font><font color=red>な</font>女
irregulare adjectives are the least common the the three groups.
Using な with い-Adjectives it is true that you can treat most いadjectives as な adjectives by replacing the final い with な 大きな問題 小さな間違い
but as far as I know this can only be used with abstract concepts. I have heard it used to discribe objects, but only when the object was a wish or desire
tigert
Of course it's a grammer point. It's providing information on certain adjectives along with their different forms.
captcouch
Should this even be on the site?
Perches
This is sometimes used as a 'na' adjective isn't it?
dcarter
Perches: Probably not, as it's vocabulary, not grammar. dcarter: Yes, as 大きな (ooki na).
KWhazit
this is not a grammar point
gandal
ゅうめい (famous) is an example of an "irregular" verb. I wouldn't really consider them "irregular" because the い in those cases are just an extension of the "e" sound.