Green’s Dictionary of Slang

ecstasy n.

also ecstacy
[ecstasy existed in the 1960s as one of many synthetic hallucinogens (although it is more amphetamine than a ‘real’ hallucinogen) from a group known as ‘Schulgin’s compounds’; it only reached its apotheosis in the late 1980s. Its nickname comes from the indiscriminate affection that its ingestion promotes, and the earlier popular name of ‘love-drug’; virtually SE by late 1990s]

a name for the drug known officially as methylenedioxymethamphetamine (MDMA).

[US]J. Stevens Storming Heaven (1988) 359: LSD [...] has been superseded by a new generation of psychedelics with names like Ecstasy, Adam, Intellex, 2CB, Vitamin K and a handful of others.
[UK]K. Lette Llama Parlour 42: ‘Oh, get real. Ecstasy.’ She looked at me expectantly. ‘MDMA?’ She rolled her eyes. ‘Methylenedioxymethamphetamine.’.
[UK]I. Welsh Trainspotting 156: Most Ecstasy hasnae any MDMA in it, lit’s just likesay, ken, part speed, part acid in its effects.
OnLine Dict. of Playground Sl. [Internet] E, ecstacy n. drug: Methylenedioxymethamphetamine (also) MDMA used mainly as part of the techno and acid house dance scene.