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4.
a mysterious disease.
She is suffering from a mysteria. Even the doctors do not know what that disease is.
by uttam maharjan July 19, 2010
 
1.
Noun.

A combination between mystery and hysteria, such as when people are hysterically interested in a mystery.

Adjectival form is mysterias
1. I was full of mysteria when my boyfriend wouldn't tell me what he had written in his notebook.
by malathia February 01, 2006
 
2.
a confusing and impossible to understand situation or place. Very complex. Only nerdy niggas will have a chance to understand a mysterium. Everybody else don't even try, your head will explode.
James: "Yo Will, girls are a mysterium. I'm trying to figure out why they crazy as hell"
Will: "You better stop man before your head explodes. Shit's crazy"
by Smart Nigga 18 July 26, 2008
 
3.
An organization made by Myst fans for Myst fans. Every year there is a convention and people vote on which city it will be in. In 2000, it was in Spokane, Washington. In 2002, it was in Carlsbad, New Mexico, in 2003 Philadelphia, Pennsylvania, in 2004 Spokane again, and 2005's will be held in Toronto, Ontario, Canada. The purpose of the conventions are to give people who have met online a chance to meet in person. There are contests and presentations at the conventions, which are held in hotels.

Plural: Mysteria, Mysteriums
"I won't be able to make it to Mysterium this year."

"The Mysterium Committee has not yet decided on a date for this year's convention."

"Mysterium.ch's discussion board is called Mystcommunity.com."

"How many Mysterium conventions have you been to?"
by Sarai February 08, 2004