The Collaborative International Dictionary of English v.0.48:

Phrenetic \Phre*net"ic\, Phrenetical \Phre*net"ic*al\, a. [L.
   phreneticus, Gr. frenhtiko`s, frenitiko`s: cf. F.
   phr['e]n['e]tique. See Frantic, and cf. Frenetic.]
   Relating to phrenitis; suffering from frenzy; delirious; mad;
   frantic; frenetic. -- Phre*net"ic*al*ly, adv.
   [1913 Webster] phreni
   phreno
   phren