mind-expander
/ˈmʌɪndɪkˌspandə/ /ˈmʌɪndɛkˌspandə/noun
Something that expands or (apparently) extends the capabilities of the mind; specifically a psychedelic drug.
Origin
Late 19th century; earliest use found in Popular Science Monthly. From mind + expander, after mind-expanding. With later use compare also mind expansion.