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.
日本語:一※
“I have one brother and two sisters.”
“The mathematician explained that one is the identity element for multiplication in any standard ring structure.”
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.
日本語:人※
“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.
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
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.”
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.”
Synonyms
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
NOUN
NUMERAL
PRONOUN
Related words
Idioms
01. as best one can
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
13. cross that bridge when one comes to it
14. cut one loose
15. damned if one does and damned if one doesn't
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
23. get back on the horse that bucked one
29. go in one ear and out the other
31. have a good one
32. have it in one
33. have one foot on a banana peel
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
46. kill two birds with one stone
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
57. make it up as one goes along
58. more than one bargained for
60. not as black as one is painted
61. not know what one is missing
62. number one
66. one age with
67. one and only
69. one brick short of a full load
70. one could do it in one's sleep
72. one fell swoop
73. one flesh
74. one for the road
77. one moment
78. one more again
79. one of His Majesty's bad bargains
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
87. one too many
88. one up
89. pinch one off
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
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
110. think one is God's own cousin
111. tie one on
113. under one roof
114. until one is blue in the face
115. wake up one day
116. whack one out
Grammar
Domain
- 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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QR code
englishreference.com/q/one
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「日本語」「カタカナ語」 data: JMdict (EDRDG), CC BY-SA 4.0