One

1. Being a single entity, unit, object, or living being.

2. Characterized by unity; undivided: They spoke with one voice.

3. 1. Of the same kind or quality: two animals of one species.

   2. Forming a single entity of two or more components: three chemicals combining into one solution.

4. Being a single member or element of a group, category, or kind: I'm just one player on the team.

5. Being a single thing in contrast with or relation to another or others of its kind: One day is just like the next.

6. Occurring or existing as something indefinite, as in time or position: He will come one day.

7. Occurring or existing as something particular but unspecified, as in time past: late one evening.

8. Informal Used as an intensive: That is one fine dog.

9. Being the only individual of a specified or implied kind: the one person I could marry; the one horse that can win this race.

1. The cardinal number, represented by the symbol 1, designating the first such unit in a series.

2. A single person or thing; a unit: This is the one I like best.

3. A one-dollar bill.

1. An indefinitely specified individual: She visited one of her cousins.

2. An unspecified individual; anyone: "The older one grows the more one likes indecency" (Virginia Woolf).

Word History: Why do we pronounce one (wŭn) and once (wŭns) while other words derived from one, like only, alone, and atone, are pronounced with a long o? Over time, stressed vowels commonly become diphthongs, as when Latin bona became buona in Italian and buena in Spanish. A similar diphthongization of one and once began in the late Middle Ages in the west of England and in Wales and is first recorded around 1400. The vowel sound underwent a series of changes, such that the word's pronunciation went from (ōn) to (ōōōn), with two syllables, to (wōn) to (wōōn) to (wŏŏn) and finally to (wŭn). In southwest England, this diphthongization happened to other words beginning with the long o sound, such as oats, pronounced there now as (wŭts). Only in one and once did this diphthongal pronunciation gain widespread usage.

Usage Note: When constructions headed by one appear as the subject of a sentence or relative clause, there may be a question as to whether the verb should be singular or plural. Such a construction is exemplified in the sentence One of every ten rotors was found defective. Although the plural were is sometimes used in such sentences, an earlier survey found that the singular was preferred by 92 percent of the Usage Panel. · Constructions such as one of those people who pose a different problem. Most grammarians would argue that who should be followed by a plural verb in these sentences, as in He is one of those people who just don't take "no" for an answer. Their thinking is that the relative pronoun who refers to the plural noun people, not to one. They would extend the rule to constructions with inanimate nouns, as in The sports car turned out to be one of the most successful products that were ever manufactured in this country. However, constructions of this sort are often used with a singular verb even by the best writers. In an earlier survey, 42 percent of the Usage Panel accepted the use of the singular verb in such constructions. Note also that when the phrase containing one is introduced by the definite article, the verb in the relative clause must be singular: He is the only one of the students who has (not have) already taken Latin. · Constructions using one or more or one or two always take a plural verb: One or more cars were parked in front of the house each day this week. One or two students from our department have won prizes. Note that when followed by a fraction, one ordinarily takes a plural verb: One and a half years have passed since I last saw her. The fraction rule has an exception in that amounts are sometimes treated as singular entities: One and a half cups is enough sugar. Note also that the plural rule does not apply to these one-plus-a-fraction constructions that are introduced by the indefinite article. These are always singular: A year and a half has passed since I last saw her. See Usage Note at he¹.

1. mod.
   having to do with something unique or special. (Similar to a definite article.) : Hank? Now there is one ugly son of a gun for you.