(1) To cause to spread out to the point of vanishing; disperse. (2) To spend wastefully or foolishly; squander.
The moderator's good humor slowly dissipated the tension that had filled the meeting room.
Dissipate suggests a gradual disintegration or vanishing, as if by crumbling, scattering, or evaporation. A police force dissipates an unruly mob. The sun dissipates the morning mist. In its second sense, dissipate implies frittering away something until it is exhausted. A foolish lottery winner might dissipate his or her money in extravagant spending sprees, buying 18 Ferraris, say, or a lifetime supply of expensive imported underwear.