Definitions
1.AdjectiveCharacterized by major progress or overcoming some obstacle."a breakthrough technological advance"
2.AdjectiveInvolving the contraction of a disease by a person with a decreased susceptibility, such as a person who has been vaccinated to help prevent that disease.
3.NounAn advance through and past enemy lines.
4.NounAny major progress; such as a great innovation or discovery that overcomes a significant obstacle."Albert Einstein is credited with making some of the greatest breakthroughs in modern physics."
5.NounThe penetration of the opposition's defence.
6.NounThe penetration of a separating wall or the remaining distance to an adjacent hollow (a crosscut in mining) or between two parts of a tunnel build from both ends.
7.NounThe emergence or one or more symptoms of a condition despite medication or other medical treatment."She was on two antiepileptics for five years but then had a breakthrough seizure.; He was managing his discomfort with common painkillers, but one morning he had breakthrough pain causing him to miss work."