major discovery, breakthrough
大発見なのに
Even though it's a major discovery...
— When Marnie Was There (2014)
それは科学において大発見の一つであった。
It was one of the great discoveries in science.
彼はいくつもの大発見で有名だ。
He is famous for several groundbreaking discoveries.
大発見だわ
What a discovery!
— サスペリア (1977)