次第（しだい）①

About

次第しだい is a noun/suffix that means can mean both "as soon as" and "depending on".

When 次第しだい means "as soon as" it attaches to the stem form of a verb, or attaches directly to a noun.

E.g. 食たべる -> 食たべ次第しだい

E.g. 確認かくにん次第しだい

This usage of 次第しだい is most commonly used to form the "As soon as X, Y" pattern.

E.g. コーヒーができ次第しだい、出発しゅっぱつしよう。

"Let's leave as soon as the coffee is ready."

When 次第しだい attaches to a する verb, it's common to drop the する stem and attach directly to the resulting noun in order to avoid the tricky to pronounce double 「し」.

E.g. 到着とうちゃく次第しだい、連絡れんらくをください。

"Please contact me as soon as you arrive."

This usage of 次第しだい may not be used with past tense sentences. Additionally, the second clause cannot feature "naturally occurring" actions.

E.g. マイクがトイレから戻もどってき次第しだい、寒さむくなった。❌

Summary

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  次第しだい can attach to a verb's stem form, or to a noun, and means "as soon as"

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  "As soon as" sentences using 次第しだい cannot be in the past tense

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  "As soon as" sentences using 次第しだい cannot have a naturally occurring action in the second clause