(idiomatic) First; foremost; best, often used after its headword.

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.

plural of number one

(idiomatic) Superlative; impossible to beat.

(idiomatic) Alternative form of look out for number one

present participle of look for number one

Third-person singular simple present indicative form of look for number one

simple past tense and past participle of look for number one

(idiomatic) To act in one's own interests; to act in a manner advantageous primarily to oneself.

Alternative form of look out for number one