Noun
the phenomenon of a popular trend attracting even greater popularity
Source: WordNetI would in fact tend to have more confidence in the outcome of a democratic decision if there was a minority that voted against it, than if it was unanimous... Social psychology has amply shown the strength of this bandwagon effect. Jürgen Habermas
in periods of high merger activity there is a bandwagon effect with more and more firms seeking to engage in takeover activity Source: Internet
polls are accused of creating a bandwagon effect to benefit their candidate Source: Internet