noun, often attributive
\ ˈglas How to pronounce glass (audio) , ˈgläs \

Definition of glass

 (Entry 1 of 4)

1 : any of various amorphous materials formed from a melt by cooling to rigidity without crystallization: such as
a : a usually transparent or translucent material consisting typically of a mixture of silicates
b : a material (such as obsidian) produced by fast cooling of magma
2a : something made of glass: such as
(1) : tumbler also : glassware
(2) : mirror
(3) : barometer
(4) : hourglass
b(1) : an optical instrument or device that has one or more lenses and is designed to aid in the viewing of objects not readily seen
(2) : field glasses, binoculars usually used in plural
c glasses plural : a device used to correct defects of vision or to protect the eyes that consists typically of a pair of glass or plastic lenses and the frame by which they are held in place

called also eyeglasses, spectacles

3 : the quantity held by a glass container
5 : crystal meth specifically : a pure form of crystal meth


glassed; glassing; glasses

Definition of glass (Entry 2 of 4)

transitive verb

1a : to provide with glass : glaze sense 1
b : to enclose, case, or wall with glass the sunroom was glassed in
2 : to make glassy
3a : reflect
b : to see mirrored
4 : to look at through an optical instrument (such as a pair of binoculars)


biographical name (1)
\ ˈglas How to pronounce Glass (audio) \

Definition of Glass (Entry 3 of 4)

Carter 1858–1946 American statesman


biographical name (2)

Definition of Glass (Entry 4 of 4)

Philip 1937–     American composer

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Other Words from glass


glassful \ ˈglas-​ˌfu̇l How to pronounce Glass (audio) \ noun
glassless \ ˈglas-​ləs How to pronounce Glass (audio) \ adjective

Synonyms for glass

Synonyms: Noun

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Examples of glass in a Sentence

Noun The waiter filled our glasses with water. She drank two glasses of water. She was wearing dark glasses with thick black frames.
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Recent Examples on the Web: Noun But the tougher team was Houston, which muscled its way on the glass. Sam Blum, Dallas News, "SMU fades late against No. 5 Houston in battle for early lead in AAC standings," 4 Jan. 2021 But the Spartans got key contributions down the stretch on the offensive glass from Thomas Kithier and Joshua Langford, then survived in the waning moments despite some wonky free-throw shooting in the final minute. Chris Solari, Detroit Free Press, "How Michigan State basketball was able to end 3-game losing streak vs. Nebraska Cornhuskers," 3 Jan. 2021 No one else averages more than 3.5, and the Toreros are minus-8.5 on the glass, 315th in the nation. Don Norcross, San Diego Union-Tribune, "Junior guard becomes leader for Toreros," 30 Dec. 2020 Despite holding the Pistons to 30% shooting in the first half, the Warriors went into the break trailing 51-48 because of the discrepancy on the offensive glass. Rusty Simmons,, "Steve Kerr says Warriors don’t expect to add a big man to the roster soon," 29 Dec. 2020 The Lakers dominated on the glass, scoring 35 second-chance points while keeping Dallas from a single putback. Dan Woike, Los Angeles Times, "LeBron James gets something almost as valuable as Lakers’ win over Mavericks," 25 Dec. 2020 Siegrist and Herlihy are also forces on the defensive glass. Alexa Philippou,, "UConn women’s basketball vs. Villanova: time, how to watch, broadcasters, preview," 22 Dec. 2020 Justin Smith is having an incredible day on the glass. Arkansas Online, "Razorbacks rally to take down Oral Roberts," 21 Dec. 2020 When their fingers met at the bottom, a flash of light reflected on the glass and there was a loud, grinding hum — the plow was finishing its work, and had swung closer., "Frozen Footsteps: A story for Christmas," 18 Dec. 2020 Recent Examples on the Web: Verb The plan was simple: Walk out to points of long ridges and glass open areas below. Jace Bauserman, Outdoor Life, "Worth the Wait: It Took 10 Years, but a Mother-Daughter Team Finally Killed Two Massive Colorado Mule Deer," 23 Dec. 2020 Years ago, the industry switched from metal backs to glass in order to facilitate wireless charging, since the RF signals couldn't penetrate metal. Ron Amadeo, Ars Technica, "Pixel 5 teardown shows off the guts of Google’s latest flagship," 2 Nov. 2020 There, several glassed-in enclosures contained multiple cubs, the couple says. Matt Wake |, al, "‘Tiger King’: Alabama ties to bonkers Netflix hit," 17 Apr. 2020 Throughout the night, Wolf zipped between the gleaming glassed-in kitchen and the dining room, touching both the tables of regulars and strangers like me. Adam Erace, Fortune, "Charleston Restaurant is the most relaxed formal dining experience in Baltimore," 8 Mar. 2020 Fit hunters glassing the Salmon River’s breaks in spring can find multiple bears on any given evening. Andrew Mckean, Outdoor Life, "The Best Black Bear Hunting Unit in the Word," 2 Apr. 2020 But some of the small glassed-in study rooms have at least four students grouped around the table, putting them much closer than six feet from each other. Alec Macgillis, ProPublica, "What’s It Like on One of the Only University Campuses Still Open in the U.S.?," 26 Mar. 2020 Colglazier was glassing when dawn broke on the Kansas rifle season. Scott Bestul, Field & Stream, "The Best Bucks of December 2019," 7 Jan. 2020 Carson’s glassed-in kitchen, perched above the entrance, overlooks the whole scene like a command center. Los Angeles Times, "Review: At Bon Temps in Downtown L.A., the brilliant desserts are only the beginning," 29 Aug. 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'glass.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of glass


before the 12th century, in the meaning defined at sense 1


14th century, in the meaning defined at transitive sense 1a

History and Etymology for glass


Middle English glas, from Old English glæs; akin to Old English geolu yellow — more at yellow

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Learn More about glass

Time Traveler for glass

Time Traveler

The first known use of glass was before the 12th century

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Statistics for glass

Last Updated

13 Jan 2021

Cite this Entry

“Glass.” Dictionary, Merriam-Webster, Accessed 24 Jan. 2021.

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More Definitions for glass


How to pronounce Glass (audio)

English Language Learners Definition of glass

 (Entry 1 of 2)

: a hard usually transparent material that is used for making windows and other products
: a drinking container made out of glass
: the amount held by a glass container



English Language Learners Definition of glass (Entry 2 of 2)

: to fit, protect, or enclose (something) with glass


\ ˈglas How to pronounce glass (audio) \

Kids Definition of glass

1 : a hard brittle usually transparent substance commonly made from sand heated with chemicals
2 : a drinking container made of glass
3 glasses plural : a pair of glass or plastic lenses held in a frame and used to help a person see clearly or to protect the eyes
4 : the contents of a glass a glass of milk


noun, often attributive
\ ˈglas How to pronounce glass (audio) \

Medical Definition of glass

1a : an amorphous inorganic usually transparent or translucent substance consisting of a mixture of silicates or sometimes borates or phosphates formed by fusion of silica or of oxides of boron or phosphorus with a flux and a stabilizer into a mass that cools to a rigid condition without crystallization
b : a substance resembling glass especially in hardness and transparency organic glasses made from plastics
2a : an optical instrument or device that has one or more lenses and is designed to aid in the viewing of objects not readily seen
b glasses plural : a device used to correct defects of vision or to protect the eyes that consists typically of a pair of glass or plastic lenses and the frame by which they are held in place

called also eyeglasses

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