An abbreviation of Quaalude, the brand name of methaqualone in the United States, an addictive, barbiturate-like sedative that can have euphoric and hypnotic effects. Especially popular in the 1960s and '70s in the US, the drug is now illegal. It was a period of my life when we used to all take a bunch of ludes whenever we would hang out, so I don't remember a lot of it very clearly. The defendant admitted to slipping the woman a lude in her drink with the aim of making her more receptive to his advances.