English Reference

Word

one

US/ˈwən/

UK/wˈɒn/

Definitions

01the number 1

A1 · Beginner Mathematics

num. the number 1, which comes before 2.

num. the first positive integer in the set of natural numbers; the cardinal number represented by the Arabic numeral 1.

“I have one brother and two sisters.”

“The mathematician explained that one is the identity element for multiplication in any standard ring structure.”

Synonyms

Antonyms

02people in general

B2 · Upper Intermediate Formal

pron. any person or people in general.

pron. an impersonal pronoun used to refer to people in general, including the speaker.

“One should always be polite to their neighbors.”

“One must consider the ethical implications before embarking on such a radical course of action.”

Usage

In modern English, 'you' is much more common than 'one' for this meaning.

Synonyms

03a special person

B1 · Intermediate Countable noun Informal

n. the perfect person for a romantic relationship.

n. a person regarded as a uniquely suitable romantic partner.

“After three years of dating, he finally realized she was the one.”

“Despite several failed relationships, she remained optimistic that she would eventually find the one.”

Synonyms

soulmate

04only or single

A2 · Elementary

adj. being the only person or thing of a particular type.

adj. functioning as a determiner or adjective to indicate a single or sole entity.

“He is the one person I can truly trust with a secret.”

“The CEO remained the one individual capable of uniting the board during the hostile takeover bid.”

Synonyms

Antonyms

05a certain time

B1 · Intermediate

adj. used to talk about a specific time in the past or future.

adj. referring to a particular but unspecified time or occasion.

“One day, I hope to travel all around the world.”

“One evening, quite unexpectedly, a letter arrived that would change the course of his professional life forever.”

Etymology

PIE word *h₁óynos From Middle English oon, on, oan, an, from Old English ān (“one”), from Proto-West Germanic ain, from Proto-Germanic ainaz (“one”), from Proto-Indo-European *h₁óynos (“single, one”). Doublet of an. Cognate with Scots ae, ane, wan, yin (“one”); North Frisian ån (“one”); Saterland Frisian aan (“one”); West Frisian ien (“one”); Dutch een, één (“one”); German Low German een; German ein, eins (“one”); Danish en (“one”); Swedish en (“one”); Norwegian Nynorsk ein (“one”), Icelandic einn (“one”); Latin ūnus (“one”) (Old Latin oinos); Russian оди́н (odín), Spanish uno. Doublet of a, an, and Uno. False cognate of Malayalam ഒന്ന് (onnŭ), Tamil ஒன்னு (oṉṉu), ஒண்ணு (oṇṇu), ஒன்று (oṉṟu). The use as an indefinite personal pronoun may have been influenced by unrelated French on, although the Germanic languages widely use cognates for the same sense (usually in non-subject function, but also in subject function, e.g. Luxembourgish een). Verb form from Middle English onen.

Analogous to several senses of Hokkien 個/个 (ê) and Mandarin 的 (de, declarative particle, nominalizer, etc.). This semantic loan might have stemmed from the apparent similarity between one as a prop-word and 的 (de) or 個 /个 (ê) as a nominalizer (e.g. 青色的 (“the green one”)). Compare Cantonese 嘅 (ge³).

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

Word family

NUMERAL

one(A1)

Related words

Idioms

01. as best one can

02. as far as one knows

03. back to square one

04. beat as one

05. become one flesh

06. bite off more than one can chew

07. bite the big one

08. bite the hand that feeds one

09. burn that bridge when one comes to it

10. close one eye

Show all 120

11. cold one

12. crawl before one walks

13. cross that bridge when one comes to it

14. cut one loose

15. damned if one does and damned if one doesn't

16. die the way one lived

17. do someone one better

18. eat an elephant one bite at a time

19. everything one touches turns to gold

20. everything one touches turns to shit

21. feed two birds with one scone

22. floor one could eat off

23. get back on the horse that bucked one

24. get it how one lives

25. get what one asked for

26. get what's coming to one

27. give as good as one gets

28. give it the big one

29. go in one ear and out the other

30. harp on one string

31. have a good one

32. have it in one

33. have one foot on a banana peel

34. have one more time

35. have one's mind about one

36. have one's wits about one

37. have one's work cut out for one

38. hit one out of the ballpark

39. hit two targets with one arrow

40. hole in one

41. I'm not the one

42. in one go

43. it takes one to know one

44. jump before one is pushed

45. keep it one hundred

46. kill two birds with one stone

47. king of all one surveys

48. last thing one needs

49. learn to walk before one can run

50. let one go

51. live one

52. look as if one had lost a shilling and found sixpence

53. look as if one has lost a shilling and found sixpence

54. look before one leaps

55. look for number one

56. look out for number one

57. make it up as one goes along

58. more than one bargained for

59. next thing one knows

60. not as black as one is painted

61. not know what one is missing

62. number one

63. number one with a bullet

64. offer one can't refuse

65. one after another

66. one age with

67. one and only

68. one big happy family

69. one brick short of a full load

70. one could do it in one's sleep

71. one could hear a pin drop

72. one fell swoop

73. one flesh

74. one for the road

75. one in the eye for

76. one man and his dog

77. one moment

78. one more again

79. one of His Majesty's bad bargains

80. one of those things

81. one side

82. one small step for man, one giant leap for mankind

83. one step ahead

84. one step forward, two steps back

85. one thing led to another

86. one thing or another

87. one too many

88. one up

89. pinch one off

90. play one against another

91. play the hand one is dealt

92. pour one out

93. pull a fast one

94. pull the other one, it's got bells on

95. put all one's eggs in one basket

96. put one foot in front of the other

97. put one over

98. put one past

99. put one's pants on one leg at a time

100. put something behind one

101. quit while one is ahead

102. reap what one sows

103. six of one, half a dozen of the other

104. square one

105. squeeze one out

106. suck a big one

107. take one for the team

108. the one that got away

109. think one hung the moon

110. think one is God's own cousin

111. tie one on

112. two birds with one stone

113. under one roof

114. until one is blue in the face

115. wake up one day

116. whack one out

117. win one for the Gipper

118. words of one syllable

119. write checks one can't cash

120. zig when one should zag

Grammar

Domain

Mathematics

This entry

Exam level
CambridgeCambridgeCambridge English QualificationsThe exam suite from Cambridge University Press & Assessment, from A1 Movers up to C2 Proficiency. The benchmark names double as CEFR labels.A1 MoversIELTSIELTSInternational English Language Testing SystemThe 0–9 band test co-owned by the British Council, IDP, and Cambridge. Used for university entry, work, and migration.2.0–3.0TOEFL iBTTOEFL iBTTest of English as a Foreign Language, Internet-Based TestETS's academic English test, the standard route for US university admissions. Scored 0–120, with a 1–6 scale since 2026.1–6 scale: 1.0–1.50–23TOEICTOEICTest of English for International CommunicationETS's workplace English test, big in Japan and Korea. Listening & Reading scores 10–990 and tops out at C1.120–224
Frequency
Very common
Level
A1 · BeginnerOxford
Updated

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