Definition of "extrados" [ex•tra•dos]

• The upper or exterior curve of an arch. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "The drawing of the arches, on the elevation, also shows exactly how the thickness of the arches is included within a precise number of earth block courses, from the intrados at the springpoint to the extrados at the keystone."
• "These spans are dictated by the coursing of the arches: the aim is to achieve high quality masonry with the height of the arch, from the intrados at the spring point to the extrados at the key-stone, contained within the height of two courses of earth blocks."
• "Infilling the extrados of the vaulting using stabilized cement mortar should also be carried out in such a way as to ensure a correct balance of the post-compression which will finally stabilize the vaulting."