Definition of "mercury"

mercury

/ˈmɜː(ɹ)kjʊɹi/

noun
countable and uncountable, plural mercuries
1. A metal.
  1. A silvery-colored, toxic, metallic chemical element, liquid at room temperature, with atomic number 80 and symbol Hg.
  2. (sciences, historical) One of the elemental principles formerly thought to be present in all metals.
  3. (with definite article) Ambient pressure or temperature (from the use of mercury in barometers and thermometers).
    Quotations
    As the mercury climbed in recent days – hovering at about 42C in both Seville and Córdoba – volunteers in both cities started to assemble around swift colonies, gathering up as many of the dehydrated and undernourished chicks they could find.
    2022 June 16, Ashifa Kassam, “‘They’re being cooked’: baby swifts die leaving nests as heatwave hits Spain”, in The Guardian‎
    Rail temperatures are checked at Manchester Piccadilly on July 18 - the first of two consecutive days in which the mercury rose above 38°C across large parts of England.
    2022 August 10, “How can we run trains when the heat is on?”, in RAIL, number 963, page 45, photo caption
  4. (obsolete) Liveliness, volatility.
    Quotations
    He was so full of mercury that he could not fix long in any friendship, or to any design.
    1724, [Gilbert] Burnet, edited by [Gilbert Burnet Jr.], Bishop Burnet’s History of His Own Time. […], volumes (please specify |volume=I or II), London: […] Thomas Ward […]
2. Any of several types of plant.
  1. An annual plant, annual mercury (Mercurialis annua), formerly grown for its medicinal properties; French mercury, herb mercury.
    Quotations
    Towards the tops of the stalks and branches come forth at every joint in the male Mercury two small round green heads, standing together upon a short footstalk, which growing ripe are the seeds, not having any flower.
    1653, Nicholas Culpeper, The English Physician Enlarged, Folio Society, published 2007, page 188
  2. Any plant of any species of the genus and the genus Mercurialis.
  3. A similar edible plant (Blitum bonus-henricus), otherwise known as English mercury or allgood.
  4. (US, regional) The poison oak or poison ivy.