- ☆ the first, usually the very best, quality or grade
- One that is first in rank, order, or importance.
- Slang One's own interests; oneself: watching out for number one.
- Informal a. The act of urinating.b. Urine.
- First in rank, order, or importance: the number one team in the nation; our number one problem.
- Foremost in quality; first-rate: bought some number one farmland.
(plural number ones)
- the most important person, the one who is in charge
- someone who is top of a ranking, who is ranked first.
- oneself, being considered foremost, as by an egoist
- (childish euphemistic) Urine; urination.
- (music) the single that has sold the most in a given period.
- (soccer) The main goalkeeper of a team, so-called because they wear the number 1 on the back of their kit.
- (cricket) The batsman who opens the batting.
- Used other than as an idiom: see number, one.