Single word break·through = we have made a major breakthrough in DNA research ˈbrākˌTHro͞o/ noun noun: breakthrough; plural noun: breakthroughs; noun: break-through; plural noun: break-throughs a sudden, dramatic, and important discovery or development. "we have made a major breakthrough in DNA research" synonyms: advance, development, step forward, success, improvement; Two words [break through something] to force your way through something that is stopping you from moving forward A group of young demonstrators attempted to break through police lines.