[ glas ]
See synonyms for glass on
  1. a hard, brittle, noncrystalline, more or less transparent substance produced by fusion, usually consisting of mutually dissolved silica and silicates that also contain soda and lime, as in the ordinary variety used for windows and bottles.

  2. any artificial or natural noncrystalline and transparent hard substance, such as fused borax, obsidian, or the like.

  1. something made of a noncrystalline and transparent hard substance, such as a windowpane.

  2. a tumbler or other comparatively tall, handleless drinking container.

  3. the quantity contained within a tumbler or other tall, handleless drinking container; a glassful: She poured two glasses of wine for herself and her guest.Drink a glass of orange juice and you'll feel better.

  4. a tumbler or other tall, handleless drinking container with its contents: Hand me that glass of milk.

  5. glas·ses, Also called eye·glas·ses [ahy-gla-siz]. /ˈaɪˌglæ sɪz/. a device to compensate for impaired vision or to protect the eyes from light, dust, and the like, consisting usually of two glass or plastic lenses set in a frame that includes a nosepiece for resting on the bridge of the nose and two sidepieces extending over or around the ears (usually used with pair of).: Compare goggle (def. 1a), pince-nez, spectacle (def. 3).

  6. a mirror.

  7. things made of glass, collectively; glassware: They used to collect old glass.

  8. a lens, especially one used as a magnifying glass.

  1. made of glass: a glass tray.

  2. furnished or fitted with panes of glass; glazed.

verb (used with object)
  1. to fit with panes of glass.

  2. cover with or encase in glass.

  1. to coat or cover with fiberglass: to glass the hull of a boat.

  2. to scan with a spyglass or other optical instrument.

  3. to reflect: Trees glassed themselves in the lake.

Origin of glass

First recorded before 900; Middle English noun glas, Old English glæs; cognate with Dutch, German Glas

Other words from glass

  • glass·less, adjective
  • glass·like, adjective
  • non·glass, adjective
  • un·glassed, adjective

Words Nearby glass

Other definitions for Glass (2 of 2)

[ glas, glahs ]

  1. Carter, 1858–1946, U.S. statesman.

  2. Philip, born 1937, U.S. composer. Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use glass in a sentence

British Dictionary definitions for glass (1 of 2)


/ (ɡlɑːs) /

    • a hard brittle transparent or translucent noncrystalline solid, consisting of metal silicates or similar compounds. It is made from a fused mixture of oxides, such as lime, silicon dioxide, etc, and is used for making windows, mirrors, bottles, etc

    • (as modifier): a glass bottle Related adjectives: vitreous, vitric

  1. any compound that has solidified from a molten state into a noncrystalline form

  1. something made of glass, esp a drinking vessel, a barometer, or a mirror

  2. Also called: glassful the amount contained in a drinking glass

  3. glassware collectively

  1. to cover with, enclose in, or fit with glass

  2. informal to hit (someone) in the face with a glass or a bottle

Origin of glass

Old English glæs; related to Old Norse gler, Old High German glas, Middle High German glast brightness; see glare 1

Derived forms of glass

  • glassless, adjective
  • glasslike, adjective

British Dictionary definitions for Glass (2 of 2)


/ (ɡlɑːs) /

  1. Philip. born 1937, US composer noted for his minimalist style: his works include Music in Fifths (1970), Akhnaten (1984), The Voyage (1992), and Monsters of Grace (1998); his film music includes scores for Kundun (1998), The Truman Show (1999), and The Hours (2002)

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 glass


[ glăs ]

  1. A usually transparent or translucent material that has no crystalline structure yet behaves like a solid. Common glass is generally composed of a silicate (such as silicon oxide, or quartz) combined with an alkali and sometimes other substances. The glass used in windows and windshields, called soda glass, is made by melting a silicate with sodium carbonate (soda) and calcium oxide (lime). Other types of glass are made by adding other chemical compounds. Adding boron oxide causes some silicon atoms to be replaced by boron atoms, resulting in a tougher glass that remains solid at high temperatures, used for cooking utensils and scientific apparatuses. Glass used for decorative purposes often has iron in it to alter its optical properties.

a closer look

Common sand and glass are both made primarily of silicon and oxygen, yet sand is opaque and glass is transparent. Glass owes its transparency partly to the fact that it is not a typical solid. On the molecular level, solids usually have a highly regular, three-dimensional crystalline structure; the regularities distributed throughout the solid act as mirrors that scatter incoming light. Glass, however, consists of molecules which, though relatively motionless like a typical solid, are not arranged in regular patterns and thus exhibit little scattering; light passes directly through. At a specific temperature, called the melting point, the intermolecular forces holding together the components of a typical solid can no longer maintain the regular structure, which then breaks down, and the material undergoes a phase transition from solid to liquid. The phase transition in glass, however, depends on how quickly the glass is heated (or how quickly it cools), due to its irregular solid structure.

The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Other Idioms and Phrases with glass


In addition to the idioms beginning with glass

  • glass ceiling
  • glass is half full, the

also see:

  • people who live in glass houses

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.