This word is acceptable for play in the US dictionary that is being used in the following games:

• Lexulous
• Wordscraper
• Wordosaur

n. The state of someone acknowledged as a megastar.

"Both, understandably, focus on the site’s power to launch new bands to megastardom, which is sexy and relatively visible, rather than its impressive ability to mortally wound even a well established group."

stardom    superstardom