Mean time and Meanwhile

Mean time noun - Astronomy) time based on the motion of the mean sun (an imaginary sun moving uniformly along the celestial equator.

Meanwhile and mean time are semantically related. In some cases you can use "Meanwhile" instead the phrase "Mean time" as a noun or an adverb.

Meanwhile noun - The time between one event, process, or period and another.

Mean time and meanwhile are semantically related. Sometimes you can replace phrase "Mean time" with "Meanwhile", this terms are similar.