noun. an antidepressant of the SSRI category. It is presently one of the most frequently rendered antidepressants. Alike to other SSRI's, it is utilized to remediate depression and anxiety-related illnesses or dysfunctions, like panic disorder, cultural phobia, and OCD. It varies from other SSRI's, because most patients are easily sedated instead of the drug being an activator- hence, it ought to be taken in the evening instead of upon waking. It shouldn't be taken by patients who are already taking MAOI's. Paroxetine is accessible in immediate and controlled-release forms. U.S. brand name: Paxil.