Quaalude is a brand-name for methaqualone (C16 H14 N2 O)... In other words, Methaqualone is a downer, a depressant, similar to barbiturates in most every way, although probably more addictive.
Derived from Quiet and Interlude.
Word History: Maalox got it's name for the "ma" in magnesium, the "al" in aluminum, and the "ox" from hydroxides. Quaalude borrowed the "aa" idea and the rest of the word perhaps derives from "quiet interlude" to describe the sedation effect.
I always talk like I'm wigged out on quaaludes.