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rheostat

From Wiktionary, the free dictionary
See also: rhéostat

English

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WOTD – 23 June 2026
A symbol for a rheostat (sense 1) used in circuit diagrams.
A drawing of Charles Wheatstone’s 1843 rheostat (sense 1) with a metal and a wooden cylinder.
The rheostat (sense 1) of a film projector.

Etymology

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Etymology tree
Proto-Indo-European *ser-?
Proto-Indo-European *srew-
Proto-Indo-European *-eti
Proto-Indo-European *sréweti
Proto-Hellenic *hréwō
Ancient Greek ῥέω (rhéō)
English rheo-
English -stat
English rheostat

    From rheo- (prefix meaning ‘current; flow’) + -stat (suffix forming the names of scientific instruments which render the prefixed elements static or stationary in some respect),[1] coined by the English physicist and inventor Charles Wheatstone (1802–1875) in an 1843 journal article: see the quotation.

    Pronunciation

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    Noun

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    rheostat (plural rheostats)

    2. (electronics, technology) An electrical resistor with two terminals, the resistance of which can be varied continuously by moving a knob or slider to regulate the flow of an electric current. [from 1843]
      Hypernym: potentiometer
      • 1843 June 15 (date delivered), Charles Wheatstone, “XIII. The Bakerian Lecture.—An Account of Several New Instruments and Processes for Determining the Constants of a Voltaic Circuit.”, in Philosophical Transactions of the Royal Society of London, volume [CXXXIII], part I, London: […] Richard and John E[dward] Taylor, […], published 1843, →OCLC, §§5–6, pages 309 and 311:
        [page 309] As the principal use of this instrument is to adjust or regulate the circuit so that any constant degree of force may be obtained, I have called it a Rheostat. […] [page 311] The rheostat, especially under the form last described, may be usefully employed as a regulator of a voltaic current in order to maintain for any required length of time precisely the same degree of force, or to change it in any desired proportion.
      • 1921 July (date written), William Schriever, The Simple Rigidity of a Drawn Tungsten Wire at Incandescent Temperatures: A Thesis Presented to the Faculty of the Graduate College of the State University of Iowa in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy, [Iowa City, Iowa]: [State University of Iowa], published 6 June 1923, →OCLC, page 259:
        The temperature was kept constant by taking pyrometer readings at the beginning, after the third set of observations, and after the sixth set of observations, and making slight adjustments in the heating-current rheostats when necessary.
      • 1953–1954, Case Kowal, “Carlisle & Finch”, in Toy Trains of Yesteryear (Rail-craft Library; C-22), Ramsey, N.J.: Model Craftsman Publishing Corporation, published 1972, →ISBN, page 4, column 2:
        Before the days of step down AC toy transformers, there was no way of regulating the speed of the electric train except that the more enterprising model train enthusiasts did use battery rheostats which could be purchased for 50¢ from electrical supply houses.
        The work contains articles reprinted from Toy Trains Magazine (1953–1954).
      1. Such a device used to regulate the brightness of an electric light; a dimmer.
        Synonym: dimmer switch
        • 1966, Alistair MacLean, “Dusk Monday – 3 a.m. Tuesday”, in When Eight Bells Toll, 1st American edition, Garden City, N.Y.: Doubleday & Company, →OCLC, page 8:
          The light in the radio cabin was very dim, the rheostat of the angled table lamp had been turned down until only a faint pool of yellow fell on the scratched metal of the table, […]
        • 2023, Paul Farmer, “Touring One & All!”, in After the Miners’ Strike: A39 and Cornish Political Theatre versus Thatcher’s Britain, volume 1, Cambridge, Cambridgeshire: Open Book Publishers, →DOI, →ISBN, page 77:
          [W]e decided we needed to carry our own theatre lighting. […] [H]e looked out for us two very large ancient round lamps with thick 'Fresnel' lenses and tall, heavy stands. To dim these lamps, there was a pair of huge rheostats mounted on a thick ply board, that inspired in the operator a constant fear of random electric shocks at 240 volts of Alternating Current.
    3. (figurative) A notional device which causes some quality to vary.
      • 1968, John D[ann] MacDonald, The Girl in the Plain Brown Wrapper, Philadelphia, Pa.; New York, N.Y.: J[oshua] B[allinger] Lippincott Company, published 1973, →ISBN, page 34:
        The world had dimmed a little when she was gone, as if there were a rheostat on the sun and somebody had turned it down, just one notch.
      • 2004, Tom Wolfe, “The Tailgaters”, in I am Charlotte Simmons, New York, N.Y.: Farrar, Straus and Giroux, →ISBN, page 312:
        You could see the giant's scorn and fury dim down all at once, as if it were on a rheostat. Obviously he was beginning to process the implications in terms of public opinion, gawker opinion, if this was in fact the girl's brother.
      • 2023 June 23, Lea Kiefer [et al.], “WAPL Functions as a Rheostat of Protocadherin Isoform Diversity that Controls Neural Wiring”, in Science, volume 380, number 6651, Washington, D.C.: American Association for the Advancement of Science, →DOI, →ISSN, →OCLC, structured abstract [conclusion], page 1, column 3:
        We propose a model in which WAPL functions as a rheostat of cohesin processivity on DNA to enable structural and transcriptional modularity of the Pcdh gene cluster required to establish different patterns of neural connectivity during brain development. […] We speculate that rheostats are solutions to the challenges imposed by the complex architectures of these gene clusters that generate the transcriptional diversity crucial for cellular and functional diversification.

    Alternative forms

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    Derived terms

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    Translations

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    References

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    1. ^ “rheostat, n.”, in OED Online Paid subscription required⁠, Oxford: Oxford University Press, June 2026; “rheostat, n.”, in Lexico, Dictionary.com; Oxford University Press, 2019–2022.

    Further reading

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    Anagrams

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