(n.) Geophysics. The duration of the passage of a signal from the source through the Earth and back to the receiver. A time seismic sectiontypically shows the two-way traveltime of the wave. Syn: traveltime. See: Acoustic Log, Average Velocity, Depth Map, Depth Migration, Isochron Map, Receiver, Signal, Sonic Log, Source, Two-Way Traveltime, Wave