Mean solar time and Meantime

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

Meantime and mean solar time are semantically related. In some cases you can replace term "Meantime" with "Mean solar time", this terms are similar.

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

Mean solar time and meantime are semantically related. You can use "Mean solar time" instead a noun "Meantime".