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