adj., n., & pron.
adj. 1 single and integral in number. 2 (with a noun implied) a single person or thing of the kind expressed or implied (one of the best; a nasty one). 3 a particular but undefined, esp. as contrasted with another (that is one view; one thing after another). b colloq. (as an emphatic) a noteworthy example of (that is one difficult question). 4 only such (the one man who can do it). 5 forming a unity (one and undivided). 6 identical; the same (of one opinion).
n. 1 a the lowest cardinal number. b a thing numbered with it. 2 unity; a unit (one is half of two; came in ones and twos). 3 a single thing or person or example (often referring to a noun previously expressed or implied: the big dog and the small one). 4 colloq. an alcoholic drink (have a quick one; have one on me). 5 a story or joke (the one about the frog).
pron. 1 a person of a specified kind (loved ones; like one possessed). 2 any person, as representing people in general (one is bound to lose in the end). 3 I, me (one would like to help). °Often regarded as an affectation. all one (often foll. by to) a matter of indifference. at one in agreement. for one being one, even if the only one (I for one do not believe it). for one thing as a single consideration, ignoring others. one another each the other or others (as a formula of reciprocity: love one another). one-armed bandit colloq. a fruit machine worked by a long handle at the side. one by one singly, successively. one day 1 on an unspecified day. 2 at some unspecified future date. one-horse 1 using a single horse. 2 colloq. small, poorly equipped. one-liner colloq. a single brief sentence, often witty or apposite. one-man involving, done, or operated by only one man. one-night stand 1 a single performance of a play etc. in a place. 2 colloq. a sexual liaison lasting only one night. one-off colloq. made or done as the only one; not repeated. one or two see OR(1). one-piece (of a bathing-suit etc.) made as a single garment. one-sided 1 favouring one side in a dispute; unfair, partial. 2 having or occurring on one side only. 3 larger or more developed on one side. one-sidedly in a one-sided manner. one-sidedness the act or state of being one-sided. one-time former. one-to-one with one member of one group corresponding to one of another. one-track mind a mind preoccupied with one subject. one-two colloq. 1 Boxing the delivery of two punches in quick succession. 2 Football etc. a series of reciprocal passes between two advancing players. one-up colloq. having a particular advantage. one-upmanship colloq. the art of maintaining a psychological advantage. one-way allowing movement or travel in one direction only.
[ OE an f. Gmc ]