1. A movement of particles in an elastic body, whether solid or fluid, that produces a progression of alternate elevations and depressions, or rarefactions and condensations. 2. The elevation of the pulse, felt by the finger or represented in the curved line of the sphygmograph. 3. The complete cycle of changes in the level of an energy source that repetitively varies over time; in the electrocardiogram and the electroencephalogram, the wave is essentially a voltage-time graph.