2number one or No. 1 adjective
: highest in rank or importance
▪ Heart disease is the country's number one [=leading] killer of women. ▪ My number one [=main] concern is getting my car fixed. ▪ The book is the company's number one seller. ▪ Rule number one is don't get caught! ▪ He's public enemy number one: the nation's most wanted criminal.
▪ Heart disease is the country's number one [=leading] killer of women. ▪ My number one [=main] concern is getting my car fixed. ▪ The book is the company's number one seller. ▪ Rule number one is don't get caught! ▪ He's public enemy number one: the nation's most wanted criminal.
