The term used for when individuals perceive a group consensus that does not exist is:

The term that describes when individuals perceive that a group consensus exists, even though it does not, is known as "Pluralistic Ignorance." This concept captures the phenomenon where people mistakenly believe that their own feelings or behaviors are different from those of the group when, in reality, others may feel the same way but are also misled by the lack of open communication or expression in the group.

In contrast, noted terms such as "False Consensus" refer to the tendency people have to assume that their behaviors and opinions are more widely shared than they really are, which is somewhat similar but not precisely capturing the absence of true consensus perceived by the individuals. The other options, "Monounic Consensus" and "Dissensus," are either less commonly discussed or refer to other concepts entirely and do not accurately describe the situation of mistakenly believing there is a consensus.

Thus, the definition aligns perfectly with the phenomenon described, establishing the understanding of how individuals can misinterpret the group dynamics at play, seeing a consensus where none exists.