What does Ms mean in the metric system?

Answer 1

An uppercase M in the metric system stands for the prefix mega, meaning one million. For instance 1Mg is one megagram, or one million grams.

Ms would mean one megasecond ( s represents seconds), or one million seconds.

Sometimes an uppercase M is mistakenly used for metre, which should be represented by a lowercase m.

Answer 2

"Ms" in the metric system typically stands for milliseconds, which is a unit of time equal to one thousandth of a second.