number one

noun

Definition of number one

 (Entry 1 of 2)

1 : one's own interests or welfare : oneself looking out for number one often written No. 1
2 : one that is first in rank, importance, or influence often written No. 1

number one

adjective

Definition of number one (Entry 2 of 2)

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

Keep scrolling for more

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.
See More

Recent Examples on the Web: Adjective

But c’mon, Kate's wardrobe is always going to be number one. Lucy Wood, Marie Claire, "Kate Middleton's Chic Lace Up Ankle Boots From LK Bennett Are On Sale," 5 Feb. 2019 Liam Doesn't Include Zayn in 1D Post Liam Payne got really excited when fans made #OneDirectionBestFans the number one trending topic worldwide on Twitter. Tamara Fuentes, Seventeen, "Are the One Direction Guys Still Friends With One Another?," 11 Mar. 2019 What's more, the artist currently has a song on Dutch Top 40 that has remained number one for nine weeks. Jennifer Lance, Glamour, "Watch How Pink and Glamour Helped Change YouTuber Davina Michelle's Life with "You Sang My Song"," 27 Dec. 2018 The program had been ranked number one for the previous four years. Susan Snyder, Philly.com, "AG's office opens probe into Temple business school scandal," 13 July 2018 The second-least populated state in the country nabbed eighth place overall for education and number one for preschool enrollment. Katie Arnold, Outside Online, "Yes, You Should Move Your Family to Vermont," 20 June 2018 America's Got Talent: The Champions is lighting up televisions every Monday night as top acts from all of the Got Talent shows around the world compete for the ultimate number one spot. Michelle Manetti, Good Housekeeping, "See Who Was Voted Off 'America's Got Talent: The Champions'," 22 Jan. 2019 Like Father was Netflix's number one movie in over 100 countries its opening weekend. Anna Moeslein, Glamour, "How Like Father Became Netflix's Unexpected Hit of the Summer," 21 Aug. 2018 Hong Kong has been ranked number one for least affordable housing for the past eight years. Alexandra Deabler, Fox News, "Number of Hong Kong McDonald's 'McRefugees' sleeping in restaurants has skyrocketed," 6 Aug. 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'number one.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

See More

First Known Use of number one

Noun

circa 1705, in the meaning defined at sense 1

Adjective

1839, in the meaning defined at sense 1

Keep scrolling for more

Learn More about number one

Statistics for number one

Look-up Popularity

Time Traveler for number one

The first known use of number one was circa 1705

See more words from the same year

Keep scrolling for more

More Definitions for number one

number one

noun

English Language Learners Definition of number one

 (Entry 1 of 2)

: a person, thing, or position that is highest in rank : the most important person or thing in a group of people or things
: the most successful person or thing in a group of people or things
: your own happiness, health, or success

number one

adjective

English Language Learners Definition of number one (Entry 2 of 2)

: highest in rank or importance

More from Merriam-Webster on number one

Thesaurus: All synonyms and antonyms for number one

Comments on number one

What made you want to look up number one? Please tell us where you read or heard it (including the quote, if possible).

WORD OF THE DAY

likely to have or produce good results

Get Word of the Day daily email!

Test Your Vocabulary

Words from Greek and Latin Quiz

  • roman forum
  • Which of the following months comes from a Latin word for “ten”?
Name That Thing

Test your visual vocabulary with our 10-question challenge!

TAKE THE QUIZ
Dictionary Devil

Test Your Knowledge - and learn some interesting things along the way.

TAKE THE QUIZ
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!