怖い indeed means both "to be scary" and "to be scared" depending on the context. You may feel this is insane, but English has similar examples, too, so let me explain about this first.
In English, "I am sad" means this person is feeling sorrow, but "The news is sad" does not mean this news is feeling sorrow. Why? Because "sad" has two distinct meanings, "to ...
だ is the plain-form copula (the "is; to be" word). In the plain form, い adjectives already form a complete predicate (the piece of a sentence or clause that can complete that sentence or clause). In translation, it's like the い adjective already includes the "is" meaning -- so 速い would be "[it] is fast", not just "fast".
Since だ is only used to provide a ...
To give a few working examples:
I'm scared of cats.
Emiko seems to be fine around cats, but apparently is scared of me.
I'm scary, just so you know.
That makes 私は怖い officially ambiguous and the answer to your question must be "both, depending on the context".
Your "usual rule" is incomplete. It should be:
if resulting is a single mora in length, add -sa
na + sa
na + sa + sou --> nasasou.
atu + sou --> atusou.
Grammatically speaking, there really are no adjectives in Japanese. i-adjectives are just special verbs. i-adjectives have many of the same inflections as do verbs, and they fulfill a grammatical role essentially equivalent to that of verbs. Therefore, 電車は速い is a complete sentence meaning "the train is fast", where 速い is the predicate.
i-adjective + です ...
As answered, 少ない is not a negative form of an adjective, but rather already the dictionary form.
It is only coincidentally pronounced the same way as the negative form of other い-adjectives.
It might be interesting to know that the dictionary entry of すくない also shows alternative kanji (including archaic versions), where the only kana visible after the ...
Thanks to snailplane's and Dono's links, it seems that the answer is fairly established:
Namely, 〜ない is also a suffix that attaches onto words describing state or quality, turns them into a 形容詞, and emphasizes them.
There are at least three types of omission of く, which should be distinguished.
The "traditional western" euphoric change is called ウ音便 and is described in this question, this one and a chart in this page. ku becomes (y)u, etc. This sounds old-fashioned and elegant. While this is commonly heard in samurai dramas, only a few courteous elder people use this ...
"Aがこわい" commonly means "A is horrible(scary)", "I am scared of A". So 私がこわい is commonly interpreted as "I am horrible(scary)". For example, 昨日、友達に意地悪をしてしまった。私がこわい.
If you want to say "I am scared", you can say "私はこわい", "私はこわがっている".
However, "Aはこわい" can mean both "A is horrible(scary)" and "A is scared", so if you clearly want to mean ""A is scared", you ...
It's uttered as a colloquial, casual and exclamatory phrase. It's typically used in response to a situation/stimulation that strikes you suddenly. っ is often added after the stem.
高っ! (Wow,) it's expensive!
やば(っ)! (Wow,) this is bad!
In formal settings, you should generally avoid this, but no one would blame you for ...
nasi and nai are the same word. Like all adjectives, nasi is the conclusive form (終止形), while nai is the attributive form (連体形). More specifically, the attributive ends in naki, but the medial -k- drops out in modern Japanese becoming nai. This is true of all adjectives: atusi -> atuki > atui, takasi -> takaki > takai, muzukasi -> muzukasiki > muzukasii etc. ...
The standard form is おもしろくて仕方ない, where おもしろくて is used as an adjective (not adverb) in the て-form for connecting predicates.
(て-form adjective) + 仕方ない
(たい-form verb in て-form) + 仕方ない
is a common phrase that means “It's so (adjective)” or “I really want to (verb)”. The nuance of this 仕方ない is “I can't stand it”, but it's not to be taken literally, ...
Is it by any chance the case that, historically, the い-adjective ending 〜かった is a contraction originating from 〜くあった, where あった is the past inflection of ある?
That's exactly what you're seeing.
For ～い adjectives, there were three base conjugation forms:
～し -- 終止形【しゅうしけい】: terminal / conclusive, for ending a sentence of clause.
～き -- 連体形【れんたいけい】: ...
there is perhaps some historical connection between the く sound and い sound, either phonologically or semantically.
I think the answer from blutorange addresses this.
Maybe these two classes of words [〜い adjectives and 〜く verbs] diverged from the same class of words somehow?
I'll disagree with blutorange about this part, as his answer is (I believe) ...
好きくない is indeed not proper grammar. It is sometimes used by children (and hence in fiction for children or childlike characters), reanalyzing 好き which should be a na-adjective 好き（な） as an i-adjective *好きい, hence *好きくない or *好きかった.
有名 is a na-adjective and thus is followed by だ・で・な・に (or by じゃ < では)
lit. that person is famous
lit. that person is a famous person
lit. that person is surely going to become famous
You can think of ではありません or じゃありません as the negative of です (which in turn is the polite form of だ whose negative would be ではない or じゃない). Hence
In this specific case, yes, 青空 and 青い空 both mean "blue sky". When used on their own, there is no surprising connotation and thus they are interchangeable. But 青空～ in a compound noun can mean "open-air" or "outdoor" (e.g., 青空教室 is not the same as 青い空教室).
Note that it's not always true for similar pairs. 白紙 is not the same as 白い紙, and 赤本 is not the same as ...
Shogakukan does list the 難有 combination with a reading of ありがた in one place, in the title of a kabuki play: 難有御江戸景清. Poking around online suggests that this is read as ありがたやめぐみのかげきよ. The reversed kanji order would match Chinese syntax better than Japanese, making me wonder if this is simply a kanbun style of spelling.
Googling a bit more brought up ...
This is not a 'productive' grammar. There are certain cases (e.g. 近い・近くの、多い・多くの) where there are both noun and i-adjective forms, but you don't generally see "高くの". Where the noun form exists it will generally have a dictionary entry as well. And of course, there are only a few basic colours which even have the i-adjective form.
For the colours, ...
This is an interesting topic but I think the question could stand to be a bit more focused. I will throw out an answer in an attempt to inspire other people to dig up better info and perhaps the OP to make the question more specific and answerable.
So "what is happening", in general terms to avoid specific theoretical assumptions:
In certain kinds of ...
It's basically that simple. So saying 寒くありません is more formal than saying 寒くない.
However, I feel that saying 寒くありません is a bit stiff even if you are trying to be polite. Instead, saying 寒くないです sounds more natural and is also more polite than leaving off the です.
デジタル大辞泉 says 遠く is a noun which means 遠いところ. So yes, it was somehow nominalized and lexicalized in this form long ago. At least we can say 遠くから来る, 遠くに行く, 遠くへ行く, 遠くを見つめる, 遠くで音がする, 遠くの国, 遠くがよく見える, and so on. 近く works in the same way.
The list of similar expressions is very small, according to this article. Here's the list:
古く (old time), 早く (early time), 遅く (...
欲しいが仮眠する is plainly wrong if it's intended to mean "I want to take a nap". It can mean "I want it, but I'll take a nap (for now)" depending on the context.
However, the following sentences make sense:
It's not that Azulim is cute, but that (being) cute is (being) Azulim! (i.e., Azulim is the only person who deserves the word cute.)...