adj.
 (madder, maddest)
    - mentally ill; insane. ▸extremely foolish or ill-advised. ▸(of a dog) rabid. 
- informal frenzied; frantic.
- informal very enthusiastic about something: 
[in combination]
 he's football-mad. 
- informal very angry.
v.
 (mads, madding, madded)
 archaic make mad.
Phrase
  
    - like mad
 informal with great intensity, energy, or enthusiasm.
- mad keen
 Brit. informal very enthusiastic.
 
  Derivative
  
  Etymology
  OE gemæd(e)d ‘maddened’, participial form rel. to gemād ‘mad’, of Gmc origin.