An archaic or obsolete form of frenzy, meaning wild excitement, violent emotion, or delirium; a state of mental confusion.
From em- (intensive prefix) + frenzy (from Greek phrenitis 'inflammation of the mind'). The em- prefix intensified the original Greek sense of brain inflammation.
Emphrensy shows how English added em- prefixes to intensify meanings, but eventually speakers realized 'frenzy' was already intense enough, so the em- version faded away.
Complete word intelligence in one call. Free tier — 50 lookups/day.