noun
or No.
[noncount] a person, thing, or position that is highest in rank :the most important person or thing in a group of people or things
I'll tell you why we can't go on a vacation: number one, we can't afford it, and number two, we'll miss my sister's party.
the most successful person or thing in a group of people or things
your own happiness, health, or success :yourself
informal :liquid waste from the body :urine - used mainly by children or when speaking to children; - compare number two
adjective
or No.
highest in rank or importance