The American Heritage® Dictionary of the English Language, 4th Edition
n. The act or practice of reasoning or decision-making by a group, especially when characterized by uncritical acceptance or conformity to prevailing points of view.
n. A process of reasoning or decision-making by a group, especially one characterized by uncritical acceptance or conformity to a perceived majority view.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. decision making by a group (especially in a manner that discourages creativity or individual responsibility)
Word Usage
"If only Macpherson had used the term groupthink instead the absurdity above wouldn't have happened."