The Collaborative International Dictionary of English v.0.48:

Boiling \Boil"ing\, a.
   Heated to the point of bubbling; heaving with bubbles; in
   tumultuous agitation, as boiling liquid; surging; seething;
   swelling with heat, ardor, or passion.
   [1913 Webster]

   Boiling point, the temperature at which a fluid is
      converted into vapor, with the phenomena of ebullition.
      This is different for different liquids, and for the same
      liquid under different pressures. For water, at the level
      of the sea, barometer 30 in., it is 212 [deg] Fahrenheit;
      for alcohol, 172.96[deg]; for ether, 94.8[deg]; for
      mercury, about 675[deg]. The boiling point of water is
      lowered one degree Fahrenheit for about 550 feet of ascent
      above the level of the sea.

   Boiling spring, a spring which gives out very hot water, or
      water and steam, often ejecting it with much force; a
      geyser.

   To be at the boiling point, to be very angry.

   To keep the pot boiling, to keep going on actively, as in
      certain games. [Colloq.]
      [1913 Webster]

WordNet (r) 3.0 (2006):

boiling point
    n 1: the temperature at which a liquid boils at sea level; "they
         brought the water to a boil" [syn: boiling point, boil]
    2: being highly angry or excited; ready to boil over; "after an
       hour of waiting I was at the boiling point"