onyx

American  

[on-iks] / ˈɒn ɪks /

noun

1. Mineralogy. a variety of chalcedony having straight parallel bands of alternating colors.

2. (not used technically) an unbanded chalcedony dyed for ornamental purposes.

3. black, especially a pure or jet black.

   The pelt of this animal can range from onyx to light brown, depending on the season.

4. Medicine/Medical. a nail of a finger or toe.

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adjective

1. made of or set with banded chalcedony.

   He wore the onyx cufflinks she had given him for his birthday.

2. black, especially jet black.

   She was a vision in black, from her onyx hair to her shiny boots.

onyx British  

/ ˈɒnɪks /

noun

1. a variety of chalcedony with alternating black and white parallel bands, used as a gemstone. Formula: SiO 2

2. a compact variety of calcite used as an ornamental stone; onyx marble. Formula: CaCO 3

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onyx Scientific  

/ ŏn′ĭks /

1. A type of chalcedony that occurs in straight and parallel bands of different colors, often black and white.

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Usage

What does onyx mean? Onyx is a gemstone that’s especially known for its opaque, all-black variety. Other varieties are black with with different-colored layers, including white. Onyx is commonly used in jewelry. Historically, onyx was popular as a material for cameos—engraved gems. Sometimes, it is dyed or artificially colored. Onyx is one of the birthstones for the month of July. It is associated with the zodiac sign Leo. The word onyx is also used to refer to a very deep black color (jet-black) or describe things that are that color. Example: In this ring, the sparkling diamonds are a perfect contrast to the jet-black onyx in the center.

Etymology

Origin of onyx

First recorded in 1250–1300; Middle English onix, from Latin onyx, from Greek ónyx “nail, claw, veined gem”; nail ( def. ), unguis ( def. )

Explanation

Onyx is a a semiprecious stone with alternating black and white bands. It's often used in jewelry. Onyx is a chalcedony, which is a type of natural stone formation composed of intergrown minerals. In the case of onyx, the colors appear in bands, mainly in black and white. Onyx is considered very attractive and it's commonly used in jewelry. It's very likely you've seen earrings or a necklace made from onyx. You might also see a trophy made from onyx, with something engraved on it. Natural formations like onyx are studied by geologists.

Example Sentences

On a sunny January morning in Florida, Donald Trump went shopping for marble and onyx for his new White House ballroom.

From Barron's • Jan. 16, 2026

But greater impact, we see, was made by the German pavilion designed by Ludwig Mies van der Rohe and Lilly Reich using Roman travertine, green marble, onyx and glass, ushering in architecture’s International Style.

From The Wall Street Journal • Jan. 14, 2026

The property was “designed for luxurious living and unforgettable entertaining” thanks to its “soaring ceilings, intricate ironwork, natural stone accents, and dramatic statement features like a floor-to-ceiling backlit onyx fireplace,” according to the listing.

From MarketWatch • Oct. 14, 2025

Arsenal charge more than £30,000-a-year to join the Diamond Club with heated seats, dining at an exclusive restaurant and an onyx bar for drinks.

From BBC • May 10, 2025

The onyx markings on their masks resemble various animals and creatures; each mask is unique.

From "The Manifestor Prophecy" by Angie Thomas