Bubble

• bub‧ble [countable]
• 1 a ball of air or gas in liquid:
• When water boils, bubbles rise to the surface.
• soap bubbles
• She was blowing bubbles in her milk with a straw.
• 2 a small amount of air trapped in a solid substance:
• Examine the glass carefully for bubbles.
• 3

   a bubble of something

  literary a small amount of a feeling:
• A bubble of anger rose in Pol's throat.
• 4 also speech bubble a circle around the words said by someone in acartoon
• 5

   the bubble bursts

  used for saying that a very successful or happy period of time suddenly ends:
• The bubble has finally burst in the mobile phone industry.
• 6

   burst/prick somebody's bubble

  to make someone suddenly realize that something is not as good as they thought it was

Definition from the Longman Dictionary of Contemporary English
Advanced Learner's Dictionary.