下さい

Imperative (命令形) form of 下さる (kudasaru, “to give”), the honorific form of 呉れる (kureru). This form is said to have either directly shifted from an earlier 下され (kudasare), which is more typical of 四段活用 (yodan katsuyō, “quadrigrade inflection”) and 五段活用 (godan katsuyō, “quintigrade inflection”); or a clipping of 下さいまし (kudasaimashi)/下さいませ (kudasaimase), which is 下さり (kudasari, continuative of 下さる) + まし (mashi)/ませ (mase, imperative of ます (masu)), altered in a process called イ音便 (i-onbin).

下(くだ)さい • (kudasai) 

1. please give me

   それを下(くだ)さい。

   Sore o kudasai.

   Please give me that.

2. (polite, imperative) please do something for me; expressing a request

   現地(げんち)に着(つ)いたら電話(でんわ)して下(くだ)さい。

   Genchi ni tsuitara denwa shite kudasai.

   Please call me when you get there.

   ゆっくり話(はな)して下(くだ)さい。

   Yukkuri hanashite kudasai.

   Please speak slowly.

• The imperative sense is either attached to the て-form (te-form) of a verb, or a noun prefixed with お (o-) or ご (go-).
• This term is usually spelled in hiragana.

• (please give me): ちょうだい (chōdai) (usually used by females)
• (please): ちょうだい (chōdai) (usually used by females); なさい (nasai) (soft but firm); な (na) (casual)