noun
the reading public; the world of readers
Refers to the collective community of readers, often used in discussions about publishing, literature, or book trends.
この小説は読書界で大きな話題になった。
This novel became a big topic in the reading public.
読書界の動向を探る。
Explore trends in the world of readers.
出版界 is 'the publishing world', focusing on the industry side, whereas 読書界 focuses on the readership side.
Compound of 読書 (reading) and 界 (world, sphere). The exact historical derivation is uncertain, but it follows a common pattern for naming communities or fields.