collaboration
/kəˌlæbəˈreɪʃn; kəˌlæbə`reʃən/ n[U]
1 ~ (with sb) (on sth); ~ (between A and B) collaborating (collaborate 1) 合作; 协作
She wrote the book in collaboration with her sister, ie They wrote it together. 她和姐姐合作写成此书.
2 ~ (with sb) helping enemy forces occupying one's country 通敌.