AU

Pronunciation (US):

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 Dictionary entry overview: What does AU mean? 

• AU (noun)
  The noun AU has 2 senses:

1. 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

2. 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)

  Familiarity information: AU used as a noun is rare.

 Dictionary entry details 

• AU (noun)

Sense 1

Meaning:

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

Classified under:

Nouns denoting substances

Synonyms:

atomic number 79; Au; gold

Hypernyms ("Au" is a kind of...):

noble metal (any metal that is resistant to corrosion or oxidation)

Hyponyms (each of the following is a kind of "Au"):

24-karat gold; pure gold (100 per cent gold)

gold dust (the particles and flakes (and sometimes small nuggets) of gold obtained in placer mining)

green gold (a gold alloy (at least 14 karat gold with silver or silver and cadmium) that has a green appearance)

guinea gold (22-karat gold from which guinea coins were made)

Holonyms ("Au" is a substance of...):

gold foil (foil made of gold)

gold leaf (a very thin form of gold foil)

gold (coins made of gold)

dental gold (an alloy of gold used in dentistry)

graphic tellurium; sylvanite (a silver-white mineral consisting of silver gold telluride; a source of gold in Australia and America)

Sense 2

Meaning:

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)

Classified under:

Nouns denoting quantities and units of measure

Synonyms:

Astronomical Unit; AU

Hypernyms ("AU" is a kind of...):

astronomy unit (a linear unit used for astronomical distances)

 Context examples 

To put it into perspective, Neptune is about 30 AU away, the Voyager 1 probe is currently just under 140 AU away, and the nearest known star Proxima Centauri is 268,770 AU away.

(Our Sun Could Have Been Born With an Evil Twin Called "Nemesis", The Titi Tudorancea Bulletin)

Also called: Nevus, Cafe au lait spot, Hemangioma, Mongolian spot, Strawberry mark

(Birthmarks, NIH)

“She might almost personify Britannia,” said he, “with her complete self-absorption and general air of comfortable somnolence. Well, au revoir, Von Bork!”

(His Last Bow, by Sir Arthur Conan Doyle)

One likes to hear what is going on, to be au fait as to the newest modes of being trifling and silly.

(Persuasion, by Jane Austen)

The FDA CBER reference standard may be assigned a specific AU unitage based on quantitative skin testing in allergic individuals, or based on specific allergen content.

(Allergy Unit, NCI Thesaurus)

Chez maman, said she, quand il y avait du monde, je le suivais partout, au salon et a leurs chambres; souvent je regardais les femmes de chambre coiffer et habiller les dames, et c'etait si amusant: comme cela on apprend.

(Jane Eyre, by Charlotte Brontë)

It finds itself very close to its host star (0.012 AU, around a hundredth of the distance between the Earth and the Sun), which itself is a medium-sized active K dwarf in the Virgo Constellation.

(Mercury Not as Rare as Previously Thought, The Titi Tudorancea Bulletin)

A distance of 500 AU is roughly 0.008 light-years, or a bit under 3 light-days.

(Our Sun Could Have Been Born With an Evil Twin Called "Nemesis", The Titi Tudorancea Bulletin)

Class 1 stars, on the other hand, tended to be closer together at around 200 AU and weren't aligned with their 'egg's' axis.

(Our Sun Could Have Been Born With an Evil Twin Called "Nemesis", The Titi Tudorancea Bulletin)

Looking closely at the distances between the stars, the researchers found all binaries separated by a gap of 500 AU or more were Class 0 and lined up with the axis of the egg-shaped cloud surrounding them.

(Our Sun Could Have Been Born With an Evil Twin Called "Nemesis", The Titi Tudorancea Bulletin)