noun, noun which may take the genitive case particle 'no'
number one in all of America; best in America
Used in contexts like rankings, competitions, or superlatives to indicate the top position across the entire United States. Often appears in news, sports, or entertainment headlines.
He is said to be the best guitarist in America.
This movie recorded the highest box-office revenue in America.
Compound of 全米 (zenbei, 'all of America') + 一 (ichi, 'one'), following the pattern of similar superlative compounds like 日本一 (nihon'ichi, 'number one in Japan').