Refers to an organized group formed for a common purpose, often with a formal or legal character. Common in contexts such as freedom of association (結社の自由).
The constitution guarantees freedom of association.
He established a new academic society.
They formed a new political association.
協会 usually names a professional or trade association (like a chamber of commerce), whereas 結社 is a more general term that can also cover political or secret societies.
組織 is a neutral word for any organized structure or organization, while 結社 highlights the voluntary founding of a society for a shared purpose.
結社 emphasizes a secretive or ideological association (sometimes criminal), while シンジケート focuses on the joint business or financial purpose of the group.
Compound of 結 (けつ, 'to tie, bind') and 社 (しゃ, 'company, society'), literally meaning 'bound society'. The term has been used since the Meiji era to translate Western concepts of association and freedom of assembly.
When he was young, he joined a certain secret society.