Au

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Definition
  1. Noun (Proper noun, abbreviation):
    • Astronomical Unit: A standard unit of measurement in astronomy, defined as the average distance from the center of the Earth to the center of the Sun. It is primarily used to express distances within our solar system.
    • Gold (chemical element): A chemical element with the symbol Au (from Latin aurum). It is a dense, soft, malleable, and ductile transition metal that appears bright yellow. It is one of the least reactive chemical elements and is often found in nature in a relatively pure form.
Usage Examples

  • Astronomical Unit (AU):

    • Mars is, on average, about 1.5 AU from the Sun.
    • The new comet will pass within 0.3 AU of Earth.
    • Scientists measured the asteroid's orbit in AU.

  • Gold (Au):

    • The chemical symbol for gold is Au.
    • The ring is made of 24-karat Au.
    • The periodic table shows Au in group 11.
Advanced Usage
  • In technical and scientific writing, AU is the standard abbreviation for and is often written in uppercase without periods.
  • In chemistry and materials science, Au is the universal symbol for the element gold, used in formulas, charts, and technical specifications.
Variants and Related Words
  • astronomical unit (n): The full term for the abbreviation AU.
  • gold (n): The common English name for the element Au.
  • aurum (n): The Latin word from which the symbol Au is derived.
Synonyms
  • For AU (astronomical unit): (None; it is a specific, standardized unit of measurement).
  • For Au (gold): bullion, gold element, precious metal.
Related Phrases
  • light-year vs. AU: While an AU measures distances within a solar system, a light-year is used for interstellar distances. One light-year is approximately 63,241 AU.
  • Au nanoparticle: A common term in nanotechnology referring to microscopic particles of gold.
Noun
  1. a unit of length used for distances within the solar system; equal to the mean distance between the Earth and the Sun (approximately 93 million miles or 150 million kilometers)
  2. a soft yellow malleable ductile (trivalent and univalent) metallic element; occurs mainly as nuggets in rocks and alluvial deposits; does not react with most chemicals but is attacked by chlorine and aqua regia

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