glacis

The glacis (sense 1.2.1) of a fortification is indicated in the above diagram by arrows.

The Krak des Chevaliers, a medieval Crusader castle in Syria, has glacis (sense 1.2.1).

The glacis of a tank (sense 1.2.2; indicated in red).

Borrowed from French glacis (“slippery surface”), derived from Old French glacier (“to glide; freeze”), the former from Latin glaciāre (“to freeze”), from glaciēs (“ice”), of uncertain origin.

• (Received Pronunciation, General American) IPA^(key): /ˈɡleɪsɪs/, /ˈɡlæsi/

• Audio (Southern England)

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• Homophone: glassy (GA pronunciation)
• Rhymes: -eɪsɪs, -æsi
• Hyphenation: glac‧is

glacis (plural glacises or glacis)

1. A gentle incline.
   • 1880, Robert Louis Stevenson, “The Old Pacific Canal: The Woods and the Pacific”, in Across the Plains: With Other Memories and Essays, London: Chatto & Windus, […], published 1892, →OCLC, page 79:

     The foam of these great ruins mounts in an instant to the ridge of the sand glacis, swiftly fleets back again, and is met and buried by the next breaker.

   1. (geomorphology) A gentle sloping landform created by the deposition or erosion of material.
   2. (military)
      1. (architecture, also figuratively) A gentle incline in front of a fortification which protects it from cannon fire and exposes attackers to more effective return fire from defenders.

         Synonym: talus

         • 1823 July 15, [Lord Byron], Don Juan. Cantos VI.—VII.—and VIII., London: […] [C. H. Reynell] for John Hunt, […], →OCLC, canto VIII, stanza XXXIV, page 128:

           [T]ook his place with solemn / Air 'midst the rest, who kept their valiant faces / And levelled weapons still against the glacis.

         • 1922 (date written; published 1926), T[homas] E[dward] Lawrence, “Book II: Opening the Arab Offensive. Chapter XX.”, in Seven Pillars of Wisdom: A Triumph, Garden City, N.Y.: Doubleday, Doran & Company, published 1937, →OCLC, page 130:

           [T]heir hearts had failed them at the silence and the blaze of lighted ships from end to end of the harbour, with eerie beams of the searchlights revealing the bleakness of the glacis they would have to cross.

      2. In full glacis plate: the angled armour plate on the front of a tank which protects it from projectiles; also (often nautical), such a plate protecting an opening (for example, on a ship).
   3. (post) A device for sorting mail which slides parcels across a sloped surface.

• risberm

• “glacis, n.”, in Lexico, Dictionary.com; Oxford University Press, 2019–2022.
• “glacis, n.”, in OED Online ⁠, Oxford, Oxfordshire: Oxford University Press, March 2023

• glacis on Wikipedia.Wikipedia
• glacis (disambiguation) on Wikipedia.Wikipedia

glacis

1. second-person singular present subjunctive of glaçar

glacis

1. past of glacar