What is the abbreviation for ecstasy?

Scientifically ecstasy is known as 3,4-methylenedioxymethamphetamine. Since that is a mouthful and is hard to say it is abbreviated to MDMA. You can abbreviate ecstasy with "X" or "XTC" but those are not official abbreviations like MDMA is. Ecstasy can also be known as Adam and if it is pure will sometimes be called Molly(Ecstasy off the street is almost never pure).