Definition of Breakthrough

Noun: breakthrough  'breyk,throo

1. A productive insight
   - discovery, find
    
2. Making an important discovery
    
3. A penetration of a barrier such as an enemy's defence

1. Pass through (a barrier)
   - crack
    
2. Penetrate
   "The sun broke through the clouds"; "The rescue team broke through the wall in the mine shaft";
   - come through
    
3. Break out
   "The tooth broke through and had to be extracted";
   - erupt, come out, push through

See also:
breakstone
breakthroughs