This verb means to reduce in number, amount or severity. It is used often in medical contexts to talk about the reduction of symptoms: "The rash has begun to dissipate." It is also used often to talk about crowds dispersing: "The fans began to dissipate when the match was finished" To dissipate meaning to waste or throw away also refers to the lessening or reduction of something: "It's such a shame you don't play the piano anymore. Your talent will dissipate." "Middle-class Americans find their income quickly dissipates after normal monthly spending." This is a formal expression used more in official communication and professional contexts.