[ ag-it ]
/ ˈæg ɪt /
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a variegated chalcedony showing curved, colored bands or other markings.
a playing marble made of this substance, or of glass in imitation of it.
Printing. a 5½-point type of a size between pearl and nonpareil.Compare ruby (def. 6).
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Origin of agate

1150–1200; Middle English ac(c)ate, achate, agaten (compare Dutch agaat,Old Saxon agāt,Old High German agat), apparently <Old French agathe or Italian agata (initial stress) ≪ Medieval Latin achātēs<Greek achā́tēs


ag·ate·like, ag·a·toid, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023


What is agate?

Agate is a variety of the mineral chalcedony (a type of quartz), specifically one with bands or stripes or other markings. It is often considered a gemstone.

It can occur in a wide variety of colors, including white, yellow, red, and black.

The key quality of agate is its banding, which is crystal that has formed in the rock.

Agate is considered a semiprecious stone, which is a label assigned to some stones that have a lesser value than those considered precious.

When used in jewelry, agate is often cut into a shape called a cabochon, which is polished but not cut into facets. When loose (not set in jewelry), they are often sold in the form of a geode or slab.

Several forms of chalcedony are considered agates if they contain banding, including the gemstones onyx and sardonyx. Specific kinds of agate are named for their colors and patterns. For example, moss agate features a green pattern that resembles moss.

Agate is one of the traditional birthstones for the months of May and June. It is associated with the zodiac sign Gemini.

Example: I bought a beautiful yellow agate geode at the rock and crystal shop.

Where does agate come from?

The first records of the word agate come from the 1100s. It comes from French, from the Latin achātēs, from the Greek akhatēs.

Agate is a variety of chalcedony with the same physical qualities as fine-grained silica quartz. Its bands are formed when silica-rich water fills empty spaces within the rock. The silica then forms crystals and gradually fills the space from the outside inward. The different colors are the result of various impurities in the water.

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What are some other forms related to agate?

  • agatelike (adjective)
  • agatoid (adjective)

What are some words that share a root or word element with agate

What are some words that often get used in discussing agate?

How is agate used in real life?

Agate is used in jewelry but is also collected as a mineral, including among crystal collectors.

Try using agate!

True or False? 

The bands in agate are formed from crystals.

How to use agate in a sentence

British Dictionary definitions for agate (1 of 3)

/ (ˈæɡɪt) /

an impure microcrystalline form of quartz consisting of a variegated, usually banded chalcedony, used as a gemstone and in making pestles and mortars, burnishers, and polishers. Formula: SiO 2
a playing marble of this quartz or resembling it
Also called: ruby printing, US and Canadian (formerly) a size of printer's type approximately equal to 5 1/2 point

Word Origin for agate

C16: via French from Latin achātēs, from Greek akhatēs

British Dictionary definitions for agate (2 of 3)

/ (əˈɡeɪt) /

Northern English dialect on the way

Word Origin for agate

C16: a-² + gate³

British Dictionary definitions for agate (3 of 3)

/ (ˈæɡeɪt) /

James (Evershed). 1877–1947, British theatre critic; drama critic for The Sunday Times (1923–47) and author of a nine-volume diary Ego (1935–49)
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for agate

[ ăgĭt ]

A type of very fine-grained quartz found in various colors that are arranged in bands or in cloudy patterns. The bands form when water rich with silica enters empty spaces in rock, after which the silica comes out of solution and forms crystals, gradually filling the spaces from the outside inward. The different colors are the result of various impurities in the water.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.