B2 an important discovery or event that helps to improve a situation or provide an answer to a problem重大进展；突破
This drug has been heralded as a major breakthrough in the fight against breast cancer.
They had minor breakthroughs but real success eluded them.
Biological research has often been a precursor to medical breakthroughs which benefit patients.
The leaders emphasized that a substantial breakthrough had been achieved, but there was more work to be done.
Researchers reported another important breakthrough in cancer research.