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勉強しなさいよ！

i know what this means.. but what is the origin of しなさい ?

Does it come from する (to do verb) ??

Is it short form of something? or what?
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2013-09-07T12:51:27.547
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2013-09-07T12:58:55.833
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question
grammar verbs
The origin of しなさい
しなさい is a verb conjugation that turns the verb する into a command (imperative
form). There are a number of imperative forms, but this one in particular
gives the nuance of "talking down" or giving advice that you feel is helpful
to the listener (but keep in mind, it carries the connotation that you know
better than the listener). This is generally how a parent would speak to his
or her child, or a teacher would talk to students.

If you're not sure whether or not it's appropriate to use in a given
situation, imagine saying it in English with the phrase "You had better". e.g:

> 勉強しなさい  
>  (You had better) study.
>
> [図書館]{としょかん}で[静]{しず}かに[喋]{しゃべ}りなさい。  
>  (You had better) talk quietly in the library.
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2013-09-07T13:14:47.597
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2020-06-17T08:18:27.500
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answer
The ーし part comes from する, indeed. It is the infinitive form, or what some
grammarians like Seiichi Makino call the "masu stem": the form of the verb
that takes －ます.

する → し → します

なさい is the imperative form of なさる, which is a honorific word which means the
same as する.

Infinitives combine with なさい to form firm, but polite orders.

For instance, telling children to sit down:

座る → 座り（ます） → 座りなさい （すわりなさい）

Or encourage them to eat:

食べる → 食べます → 食べなさい

The し arises when the verb is any one of those formed by -する, or anything else
whose masu form ends in し. For instance, 押す → 押し（ます）

ボタンを押しなさい

Here, definitely there is no しなさい as a unit; since 押し is a unit!

You have probably heard しなさい by itself, though (when し is from する):

あなたも、そうしなさい。 (You too, do the same!)
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2013-09-07T16:22:39.923
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answer