dis·si·pate / ˈdisəˌpāt/ • v. 1. [intr.] disperse or scatter: the cloud of smoke dissipated. ∎  (of a feeling or other intangible thing) disappear or be dispelled: the concern she'd felt for him had wholly dissipated. ∎  [tr.] cause (a feeling or other intangible thing) to disappear or disperse: he wanted to dissipate his anger.2. [tr.] squander or fritter away (money, energy, or resources): he had dissipated his entire fortune. ∎  (usu. be dissipated) Physics cause (energy) to be lost, typically by converting it to heat.DERIVATIVES: dis·si·pa·tive / -ˌpātiv/ adj.dis·si·pa·tor / -ˌpātər/ (also dis·si·pat·er) n.

dissipate scatter, dispel XV; squander; distract XVII. f. pp. stem of L. dissipāre, f. DIS- 1 + *supāre, *sipāre throw; see -ATE 3.
So dissipation dissolution XV; †dispersion XVI; squandering XVII; distraction of mind XVIII, (hence) frivolous diversion, (passing into) dissolute living XVIII. — (O)F. or L.