~くれ
The word, くれ
, is a special word.
The original form of this is くれる (呉れる)
and the imperative form is くれろ
, while it's a deprecated expression.
According to Daijirin:
〔命令形は「くれ」が普通〕
その動作者{どうさしゃ}が話{はな}し手{て}または話題{わだい}の人物{じんぶつ}のために何{なん}らかの動作{どうさ}をすることを表{あらわ}す
(Translation: [くれ
is general in imperative form]
This means that the hearer do thing for speaker or another person.)
Daijirin says that くれ
is general and it implies that くれ
is a special case.
According to Wikipedia:
ラ行{ぎょう}下一段{しもいちだん}活用{かつよう}に属{ぞく}する「呉(く)れる」は、一般{いっぱん}に命令形{めいれいけい}が「くれ」となる。ただし方言{ほうげん}や古{ふる}い口語{こうご}では「くれろ」となることもある。
(Translation: くれる
belong to ラ行{ぎょう}下一段{しもいちだん}活用{かつよう} group. Its imperative form is くれ
generally. But in some dialects or old use, it will be くれろ
sometimes.)
My impression is that this word has varied in special way like する
and 来{く}る
.
する
belong to the unique conjugation called サ行{ぎょう}変格{へんかく}活用{かつよう}
, and only this word belongs to this conjugation group. Also 来{く}る
belongs カ行変格活用
in similar way.
Both する
and 来る
have varied in special way because they are very very old word and are used very often.
気をつけ
The example you showed, 気{き}をつけ
, is spoken by captain, leader, teacher and some person like them. I think 気をつけ
is used like noun because person like teachers use this word like below when they make children stand at attention:
気をつけ しよう。
気をつけの 姿勢{しせい}に なって。
(Both can be translated as: Stand at attention.)
It is interesting that 気をつけろ
doesn't mean Stand at attention.
; it simply means Pay attention.
はじめ
Person like teachers use this when an exam begins. For example:
(試験{しけん}、)はじめ!
(Translation: Begin your exam.)
It's similar to 気をつけ
and used widely. We can declare the beginning of something with this, while 気をつけ
means only Stand at attention.
用意{ようい}、はじめ!
(Translation: Get set, go! / start!)
Another example: やめ
This and はじめ
are used together in many cases. It's similar to 気をつけ
and はじめ
that it's used like a noun.
試験、はじめ! -> やめ!
(Translation: Begin your exam. -> Stop writing.)
EDIT
In the other words, I wanted to say that:
くれ
is a conjugation of くれる
.
つけ
is NOT a conjugation of つける
; it's a noun. But on 気をつけ
, Japanese includes me feel like whole 気をつけ
constructs one noun. Here is a reference.
はじめ
is NOT a conjugation of はじめる
; it's also a noun. Declaring the beginning of something with this word is a special use.
やめ
is NOT a conjugation of やめる
. Furthermore, やめ
, やめろ
and やむ
are not a conjugation of each other except a few cases (the cases are written below).
やめ = (noun) やめること。中止{ちゅうし}。とりやめ。
やめる = (transitive verb) 1. 続{つづ}けてきたことを,終{お}わりにする。 2. しようとしていたことを,しないことにする。
やむ = (intransitive verb) 1. それまで続{つづ}いていたことが,切{き}れて続{つづ}かなくなる。 … 〔「止{や}める」に対{たい}する自動詞{じどうし}〕
In old Japanese, やむ
has a transitive meaning. In modern Japanese, the transitive meaning is no longer available.
Why traffic signs say とまれ
instead of やめろ
is that とまれ
and やめろ
is a different word (even if they use same Kanji 止
.)
Basic meanings
やめろ (Stop doing that. (To a human))
とまれ (Stop moving. (To something moving, not only a human))
とめろ (Stop moving something. (To a human))
Example of above
私は車を運転するのをやめる。 (I stop driving a car.)
車がとまる。 (A car stops.)
私は車をとめる。 (I stop a car.)
Well, I thought it's funny that the sign doesn't ask human to stop his/her car. But any way, the word on traffic sign is とまれ
.
A exception of use of やめ
In a few cases, やめ
is used like a imperative verb. The targets are the nature or some awesome things in most cases.
雨{あめ}よ止{や}め! (Stop raining! (To the nature))
木枯{こが}らしよ止{や}め! (Stop blowing! (To the nature))
noun(+da)
ando+inf.(+da)
are often used as imperatives, such as, 起立, 突撃, お休み, etc. I think they are more like giving instructions. As for 気がつく/気をつける, I think it's one verb consisting of four/five syllables rather than a verb phrase. For example, we have 気がつかせる. 気をつけ and はじめ are also nouns.