Number one has 5 different meanings across 1 category:
Noun
Noun
1
a reference to yourself or myself etc.; `take care of number one' means to put your own interests first
2
the first or highest in an ordering or series
"He wanted to be the first"
3
the first element in a countable series
"the first of the month"
4
The most important person, the one who is in charge.
Adjective
1
First; foremost; best, often used after its headword.
Broader Terms (hypernyms)
Narrower Terms (hyponyms)