WordNet (r) 3.0 (2006):

solitary wave
    n 1: (physics) a quantum of energy or quasiparticle that can be
         propagated as a traveling wave in nonlinear systems and is
         neither preceded nor followed by another such disturbance;
         does not obey the superposition principle and does not
         dissipate; "soliton waves can travel long distances with
         little loss of energy or structure" [syn: soliton,
         soliton wave, solitary wave]