Groupthink is a term introduced by Irving Lester Janis in 1972, referring to a process where members of a cohesive group unknowingly make unanimity rather than the best decision their goal. Faulty decisions attributable to groupthink can have disastrous consequences, the explosion of space shuttle Challenger in 1986 being a well-known example.
Sources:
Janis, Irving, (1982). “Groupthink: Psychological Studies of Policy Decisions and Fiascoes
Griffin, R. W., Moorhead, G. (2011). “Organizational behavior: Managing people and organizations (10th ed.)