number one

(noun) a reference to yourself or myself etc.; `take care of number one' means to put your own interests first. Synonyms: number one.

(noun) the first or highest in an ordering or series. Synonyms: first, number one. Example: "He wanted to be the first."

(noun) the first element in a countable series. Synonyms: first, number one, number 1. Example: "The first of the month."