| Noun | 1. | phrenitis - inflammation of the brain usually caused by a virus; symptoms include headache and neck pain and drowsiness and nausea and fever (`phrenitis' is no longer in scientific use)inflammation, redness, rubor - a response of body tissues to injury or irritation; characterized by pain and swelling and redness and heat West Nile encephalitis - encephalitis caused by the West Nile virus; can be fatal in humans and horses and birds | |