a drug used to treat the illness of depression She's been on Prozac for two years. See related entries: Mental health care Culture Prozac first became available in 1988 and many users claimed it helped them. It soon became very popular for general use, especially in the US. In recent years some people have become worried about a possible link with suicide and violent behaviour. In 2004 authorities in the US decided that a warning must be given on packets of the drug that it can cause children to become suicidal (= to want to kill themselves). Word Origin 1980s: an invented name.