愛書[aisho] great love of books
愛読書[aidokusho] favourite book
悪書[akusho] harmful book
案内書[annaisho] guidebook
移動図書館[idoutoshokan] mobile library

遺言書[yuigonsho] testament
遺書[isho] note left by dead person
医書[isho] medical book
一つ書き[hitotsugaki] an item
一書[issho] one letter

ストックホルム症候群[sutokkuhorumushoukougun] Stockholm syndrome
亜群[agun] subgroup
一群[ichigun] group
一群れ[hitomure] group
可換群[kakangun] Abelian group

魚群[gyogun] school of fish
繰込み群[kurikomigun] renormalisation group (physics)
群がる[muragaru] to swarm
群れ[mure] group