Momentum/məʊˈmentəm/ Definition 1 of 4Pro Tip 1/2Gaining Strength Momentum implies increasing power, like something getting faster or stronger over time. The campaign started slow but gained momentum with each rally. Pro Tip 2/2Not Instant Momentum takes time to build; it's not immediate, but a gradual process. Her ideas took a while to catch on, but now they have considerable momentum.