Cooperate secretly is an activity that involves two or more people working together in a clandestine manner. The crossword solutions for this term are 'CONSPIRE' (8 letters) and 'CONNIVE' (7 letters). CONSPIRE means to plan or act together secretly, often with the intention of doing something unlawful or harmful. CONNIVE means to cooperate or collaborate in a secret or devious way, usually with the intent of achieving a dishonest or immoral goal.