A class of medications originally designed to treat depression and other mood disorders. There are many kinds of antidepressants, from the newer SSRIs (Selective Serotonin Reuptake Inhibitors) and SNRIs (Selective Norepinephrine Reuptake Inhibitors), as well as the older and less frequently prescribed tricyclics and MAOIs. Some antidepressants are also useful for treating anxiety disorders.