Breakthrough

Breakthrough or break through may refer to:

• Tunnel hole-through, also known as breakthrough, when the two ends of a tunnel under construction meet
• Breakthrough (military), a situation where an offensive force has broken through an enemy defensive line
• Emergency breakthrough, a function on land-line telephones that allows a caller to interrupt a phone conversation of another caller
• Epiphany (feeling), an experience of sudden enlightenment or of intellectual discovery
• Breakthrough infection, a case of illness in which a vaccinated individual becomes sick from the same illness that the vaccine is meant to prevent

Look up breakthrough in Wiktionary, the free dictionary.