noun
first championship; first title win
Used in sports and competitions for winning a championship or title for the first time. Often seen in news headlines.
彼は今年、全米オープンで初制覇を果たした。
He achieved his first championship at the US Open this year.
チームは悲願の初制覇を成し遂げた。
The team accomplished their long-awaited first title win.
Compound of 初 (first) and 制覇 (conquest, championship). The exact historical derivation is uncertain, but the word is a modern coinage used primarily in sports contexts.