The Steinhaus-Moser number ②
"The spacecraft performed a successful mega maneuver to gain additional speed before entering orbit around Mars."
Abbreviation of Moon-Earth gravity assist.
In plain English: Mega is not really used as a noun on its own, but when you see it attached to other words, it means something huge or extremely large.
"The concert featured three musical mega-stars who had sold out stadiums across the country."
Very large.
"The mega stadium held over 100,000 spectators for the championship game."
extremely
"The mega disaster left thousands homeless across the region."
A placename
"Mega is often used as a prefix in names like Megacity, but it can also appear directly in place names such as Mega City, Florida, which was named to reflect its large size."
A town in Dire, Borena, Ormia, Ethiopia
"The travelers spent the night at the small market in Mega before continuing their journey through Dire."
The word comes from the Ancient Greek prefix megas, meaning "great," "large," or "mighty." It was originally used to denote something of great size or power.