break·through 
/ˈbreɪkˌθru:/ noun
plural - throughs
/ˈbreɪkˌθru:/ noun[count] 1 : a sudden increase in knowledge, understanding, etc. : an important discovery that happens after trying for a long time to understand or explain something
▪ Researchers say they have made/achieved a major breakthrough in cancer treatment. ▪ a scientific breakthrough ▪ The police have announced a breakthrough in the murder case. — sometimes used before another noun ▪ breakthrough ideas/products
2 : a person's first important success
▪ This job could be the breakthrough she's been waiting for. — sometimes used before another noun ▪ a breakthrough performance/role/album — see also break through at 1break
▪ Researchers say they have made/achieved a major breakthrough in cancer treatment. ▪ a scientific breakthrough ▪ The police have announced a breakthrough in the murder case. — sometimes used before another noun ▪ breakthrough ideas/products
▪ This job could be the breakthrough she's been waiting for. — sometimes used before another noun ▪ a breakthrough performance/role/album — see also break through at 1break