1. [n]  any of various devices in which air or some other gas is bubbled through a liquid
2. [n]  a public fountain to provide a jet of drinking water

BUBBLER is a 7 letter word that starts with B.

1. \Bub"bler\, v. t.
   To cheat; to deceive.
   
         She has bubbled him out of his youth.    --Addison.
   
         The great Locke, who was seldom outwitted by false
         sounds, was nevertheless bubbled here.   --Sterne.
   
   

2. \Bub"bler\, n.
   1. One who cheats.
   
            All the Jews, jobbers, bubblers, subscribers,
            projectors, etc.                      --Pope.
   
   2. (Zo["o]l.) A fish of the Ohio river; -- so called from the
      noise it makes.