Proliferate/prəˈlɪfəreɪt/ Definition 1 of 2Pro Tip 1/3Quick Expansion Use 'proliferate' when something grows or increases rapidly and extensively. Mobile apps have started to proliferate across the internet. Pro Tip 2/3Negative Connotation Often has a negative connotation, suggesting uncontrollable or excessive growth. Conspiracy theories tend to proliferate online during a crisis. Pro Tip 3/3Unintended Spread Suggests spreading despite efforts to control or is unplanned. Once the rumor started, it proliferated through the school.