PHREN'ITIS, n. [Gr. from the mind; L. animus, animosus,and the Teutonic mod; Eng. mood.]

1. In medicine, an inflammation of the brain, or of the meninges of the brain, attended with acute fever and delirium.

2. Madness, or partial madness; delirium; phrenzy. [It is generally written in English, phrensy or frenzy.