number one

nouns

a reference to yourself or myself etc.; `take care of number one' means to put your own interests first
number one
domain usage
a colloquial expression; characteristic of spoken or written communication that seeks to imitate informal speech
colloquialism
is a type of (narrower)
a person considered as a unique individual
"one's own self"
self
the first or highest in an ordering or series
"He wanted to be the first"
first, number one
the first element in a countable series
"the first of the month"
first, number 1, number one