界(かい)

かい
noun, suffix
world; realm; sphere
society
1. world; realm; sphere; circle
A specific field, domain, or community of people sharing a common profession, interest, or characteristic. Often used as a suffix.
There was a big change in the political world.
Academic conferences are important gatherings in the scholarly world.

界(かい) is primarily used as a suffix meaning "world" or "realm" attached to a field, profession, or domain. It is rarely used as a standalone word.

Compounds

Usage

The pattern is [field]界(かい) to refer to the community of people and institutions in that field. Some fields use a one-kanji short form: 政界(せいかい) (politics), 財界(ざいかい) (business), 学界(がっかい) (academia).

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Common in news reporting and formal writing when discussing professional fields.