Grammar Point
expressions (phrases, clauses, etc.)
exp 
word usually written using kana alone
uk 
なさい

do ...

imperative form often used after the -masu stem of a verb

Verb ます stem + なさい

A polite but firm imperative used by people in positions of authority, such as parents or teachers, when giving instructions to those of lower status or younger age.

Standard Verb Usage

To form this command, take the ます stem of any verb and attach なさい. This creates a directive that expects obedience.

Please eat your vegetables.

Go to sleep quickly.

Read this book.

Do your homework.

Note

While なさい is polite in its grammatical form, it is still a command and can sound bossy or condescending if used toward a superior or someone of equal status in a formal setting. It is most commonly used in household or educational environments. It is sometimes colloquially shortened to just な (e.g., 食べなさい becomes 食べな).

Words: 
為さいなさい
Radicals of radicals