Before revision: In physics, the wavefront of a time-varying field is the set (locus) of all points where the wave has the same phaseof the sinusoid .Essential Principles of Physics, P. M. Whelan, M. J. Hodgeson, 2nd Edition, 1978, John Murray, The term is generally meaningful only for fields that, at each point, vary sinusoidally in time with a single temporal frequency (otherwise the phase is not well defined).
After revision: In physics, the wavefront of a time-varying field is the set (locus) of all points having the same phasewave .Essential Principles of Physics, P. M. Whelan, M. J. Hodgeson, 2nd Edition, 1978, John Murray, The term is generally meaningful only for fields that, at each point, vary sinusoidally in time with a single temporal frequency (otherwise the phase is not well defined).