The Collaborative International Dictionary of English v.0.48:

Boil \Boil\ (boil), v. i. [imp. & p. p. Boiled (boild); p. pr.
   & vb. n. Boiling.] [OE. boilen, OF. boilir, builir, F.
   bouillir, fr. L. bullire to be in a bubbling motion, from
   bulla bubble; akin to Gr. ?, Lith. bumbuls. Cf. Bull an
   edict, Budge, v., and Ebullition.]
   1. To be agitated, or tumultuously moved, as a liquid by the
      generation and rising of bubbles of steam (or vapor), or
      of currents produced by heating it to the boiling point;
      to be in a state of ebullition; as, the water boils.
      [1913 Webster]

   2. To be agitated like boiling water, by any other cause than
      heat; to bubble; to effervesce; as, the boiling waves.
      [1913 Webster]

            He maketh the deep to boil like a pot. --Job xii.
                                                  31.
      [1913 Webster]

   3. To pass from a liquid to an a["e]riform state or vapor
      when heated; as, the water boils away.
      [1913 Webster]

   4. To be moved or excited with passion; to be hot or fervid;
      as, his blood boils with anger.
      [1913 Webster]

            Then boiled my breast with flame and burning wrath.
                                                  --Surrey.
      [1913 Webster]

   5. To be in boiling water, as in cooking; as, the potatoes
      are boiling.
      [1913 Webster]

   To boil away, to vaporize; to evaporate or be evaporated by
      the action of heat.

   To boil over, to run over the top of a vessel, as liquid
      when thrown into violent agitation by heat or other cause
      of effervescence; to be excited with ardor or passion so
      as to lose self-control.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Boil \Boil\, n.
   Act or state of boiling. [Colloq.]
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Boil \Boil\, n. [Influenced by boil, v. See Beal, Bile.]
   A hard, painful, inflamed tumor, which, on suppuration,
   discharges pus, mixed with blood, and discloses a small
   fibrous mass of dead tissue, called the core.
   [1913 Webster]

   A blind boil, one that suppurates imperfectly, or fails to
      come to a head.

   Delhi boil (Med.), a peculiar affection of the skin,
      probably parasitic in origin, prevailing in India (as
      among the British troops) and especially at Delhi.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Boil \Boil\, v. t.
   1. To heat to the boiling point, or so as to cause
      ebullition; as, to boil water.
      [1913 Webster]

   2. To form, or separate, by boiling or evaporation; as, to
      boil sugar or salt.
      [1913 Webster]

   3. To subject to the action of heat in a boiling liquid so as
      to produce some specific effect, as cooking, cleansing,
      etc.; as, to boil meat; to boil clothes.
      [1913 Webster]

            The stomach cook is for the hall,
            And boileth meate for them all.       --Gower.
      [1913 Webster]

   4. To steep or soak in warm water. [Obs.]
      [1913 Webster]

            To try whether seeds be old or new, the sense can
            not inform; but if you boil them in water, the new
            seeds will sprout sooner.             --Bacon.
      [1913 Webster]

   To boil down, to reduce in bulk by boiling; as, to boil
      down sap or sirup.
      [1913 Webster]

WordNet (r) 3.0 (2006):

boil
    n 1: a painful sore with a hard core filled with pus [syn:
         boil, furuncle]
    2: the temperature at which a liquid boils at sea level; "they
       brought the water to a boil" [syn: boiling point, boil]
    v 1: come to the boiling point and change from a liquid to
         vapor; "Water boils at 100 degrees Celsius" [ant: freeze]
    2: immerse or be immersed in a boiling liquid, often for cooking
       purposes; "boil potatoes"; "boil wool"
    3: bring to, or maintain at, the boiling point; "boil this
       liquid until it evaporates"
    4: be agitated; "the sea was churning in the storm" [syn:
       churn, boil, moil, roil]
    5: be in an agitated emotional state; "The customer was seething
       with anger" [syn: seethe, boil]