number one

1 of 2

noun

plural number ones

1

a

: one's own interests or welfare : oneself

It's time to take care of number one

—often written No. 1

Looking out for No. 1 is not a selfish thing when it comes to rescuing someone, area firefighters learned.

—Cathy Spaulding

b

: one that is first in rank, importance, or influence

Who's number one in this office?

Madonna has just made a big announcement. The "Material Girl" … will release not one, but two new collections. One will feature 50 number ones with the other being a 16-track version of the album.

—Edward Pevos

—often written No. 1

The Texas Tech men's golf team, which has finished among the top three in each of its three tournaments this season, is No. 1 in the GolfStat ranking that was released Wednesday.

—Lubbock (Texas) Avalanche-Journal (online)

2

informal : liquid waste from the body : urine

—used euphemistically

When astronauts go number one, a slight vacuum in the toilet pulls urine into a low-pressure chamber, which forces the water to evaporate.

—Kaitlin Sullivan

compare number two

number one

2 of 2

adjective

1

: first in rank, importance, or influence : foremost

cancer is the country's number one killer

—often written No. 1

2

: of highest or of high quality

Synonyms

Adjective

• arch
• big
• capital
• cardinal
• central
• chief
• dominant
• first
• foremost
• grand
• great
• greatest
• highest
• key
• leading
• main
• master
• numero uno
• overbearing
• overmastering
• overriding
• paramount
• predominant
• preeminent
• premier
• primal
• primary
• principal
• prior
• sovereign
• sovran
• supreme

Examples of number one in a Sentence

Noun

Who's number one in this office?

Getting the car fixed is number one on my list of priorities.

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.

Her movie is currently number one at the box office.

When the goal was scored, the fans started to chant, “We're number one, we're number one.”

I've been taking care of other people for too long. It's time for me to take care of number one.

Adjective

The book is the company's number one seller.

Rule number one is don't get caught!

He's public enemy number one: the nation's most wanted criminal.

Recent Examples on the Web

Noun

Authorities say smoking causes some 80,000 deaths a year in the U.K, and remains the number one preventable cause of death, disability and poor health. —Sylvia Hui, Quartz, 17 Apr. 2024

Clark, the point guard phenom out of Iowa who was the number one overall pick in the 2024 WNBA draft, celebrated her milestone achievement alongside her boyfriend, fellow player McCaffery, who at 23, is no slouch on the court, either, having played in college and is now pursuing a coaching career. —Elizabeth Logan, Glamour, 16 Apr. 2024

Word History

First Known Use

Noun

1705, in the meaning defined at sense 1a

Adjective

1839, in the meaning defined at sense 1