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one

num. · pron. · n. · adj.
US //ˈwən// UK //wˈɒn// one
  1. 1 the number 1 (num.)
    A1 Beginner Math

    the number 1, which comes before 2.

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

    Example

    I have one brother and two sisters.

    Example

    The mathematician explained that one is the identity element for multiplication in any standard ring structure.
  2. 2 people in general (pron.)
    B2 Upper Intermediate Formal

    any person or people in general.

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

    Example

    One should always be polite to their neighbors.

    Example

    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.
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  1. 3 a special person (n.)
    B1 Intermediate Informal

    the perfect person for a romantic relationship.

    a person regarded as a uniquely suitable romantic partner.

    Example

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

    Example

    Despite several failed relationships, she remained optimistic that she would eventually find the one.
    • soulmate
  2. 4 only or single (adj.)
    A2 Elementary

    being the only person or thing of a particular type.

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

    Example

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

    Example

    The CEO remained the one individual capable of uniting the board during the hostile takeover bid.
  3. 5 a certain time (adj.)
    B1 Intermediate

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

    referring to a particular but unspecified time or occasion.

    Example

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

    Example

    One evening, quite unexpectedly, a letter arrived that would change the course of his professional life forever.
Etymology 1

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.

Etymology 2

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).

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