Editing Dome (section)

== Definitions ==
Across the ancient world, curved-roof structures that would today be called domes had a number of different names reflecting a variety of shapes, traditions, and symbolic associations.{{efn|name=Smith definitions 1950b}}{{efn|name=Smith definitions 1950a}}{{efn|name=Downey definitions 1945}}{{efn|name=Mainstone definitions 2000a}} The shapes were derived from traditions of pre-historic shelters made from various impermanent pliable materials and were only later reproduced as vaulting in more durable materials.{{efn|name=Smith definitions 1950b}} The hemispherical shape often associated with domes today derives from Greek geometry and Roman standardization, but other shapes persisted, including a pointed and bulbous tradition inherited by some early Islamic mosques.{{efn|name=Smith definitions 1950c}}

Modern academic study of the topic has been controversial and confused by inconsistent definitions, such as those for cloister vaults and domical vaults.{{efn|name=Dodge definitions 1984a}}{{efn|name=Dodge definitions 1984b}} Dictionary definitions of the term "dome" are often general and imprecise.{{efn|name=Chilton definitions 2000a}} Generally-speaking, it "is non-specific, a blanket-word to describe an<!-- Use of "an", rather than "a", is from the quoted source --> hemispherical or similar spanning element."{{efn|name=Dodge definitions 1984a}}{{efn|name=Osborne definitions 2004}} Published definitions include: hemispherical roofs alone;{{efn|name=Saylor definitions 1994}}{{efn|name=Parker definitions 2003}}{{efn|name=Gorse definitions 2012}} revolved [[arch]]es;{{efn|name=Coates definitions 2009}}{{efn|name=Guedes definitions 2016}}{{efn|name=Palmer definitions 2016}} and vaults on a circular base alone,{{efn|name=Dodge definitions 1984c}}{{efn|name=Trachtenberg definitions 1986}}{{efn|name=Fleming definitions 1991}}{{efn|name=Curl definitions 2003}}{{efn|name=Ambrose definitions 2008}}{{efn|name=Clarke definitions 2010}}{{efn|name=Ching definitions 2011}}{{efn|name=Burden definitions 2012}} circular or polygonal base,{{efn|name=Kurtz definitions 2004}}{{efn|name=Ching definitions 2007}}{{efn|name=Davies definitions 2008}}{{efn|name=Parker definitions 2012b}}{{efn|name=Davies definitions 2012}} circular, elliptical, or polygonal base,{{efn|name=Cowan definitions 1998}}{{efn|name=McNeil definitions 2002}}{{efn|name=Curl definitions 2015}} or an undefined area.{{efn|name=Heyman definitions 1997}}{{efn|name=Mainstone definitions 2000b}}{{efn|name=Harris definitions 2005}}{{efn|name=Brett definitions 2012}}{{efn|name=Hourihane definitions 2012}}{{efn|name=Harris definitions 2013}}{{efn|name=Murray definitions 2013}} Definitions specifying vertical sections include: semicircular, pointed, or bulbous;{{efn|name=Trachtenberg definitions 1986}}{{efn|name=Harris definitions 2005}}{{efn|name=Harris definitions 2013}} semicircular, segmental or pointed;{{efn|name=Burden definitions 2012}}{{efn|name=Brett definitions 2012}} semicircular, segmental, pointed, or bulbous;{{efn|name=Fleming definitions 1991}}{{efn|name=Curl definitions 2003}}{{efn|name=Ambrose definitions 2008}}{{efn|name=Clarke definitions 2010}}{{efn|name=Curl definitions 2015}} semicircular, segmental, elliptical, or bulbous;{{efn|name=McNeil definitions 2002}} and high profile, hemispherical, or flattened.{{efn|name=Murray definitions 2013}} Domes with a circular base are called "circular domes", regardless of the shape of their cross-section.{{sfn|Capone|Lanzara|2019|p=220}}

[[File:Arc truefalserp.jpg|thumb|right|Comparison of a generic "true" [[arch]] (left) and a corbel arch (right)]]
Sometimes called "false" domes, [[Corbel arch|corbel]] domes achieve their shape by extending each horizontal layer of stones inward slightly farther than the lower one until they meet at the top.{{sfn|Huerta|2007|p=212}} A "false" dome may also refer to a wooden dome.{{sfn|Hourihane|2012|p=302}} The Italian use of the term ''finto'', meaning "false", can be traced back to the 17th century in the use of vaulting made of reed mats and gypsum mortar.{{sfn|Nobile|Bares|2015|p=4}} "True" domes are said to be those whose structure is in a state of compression, with constituent elements of wedge-shaped [[voussoir]]s, the joints of which align with a central point. The validity of this is unclear, as domes built underground with corbelled stone layers are in compression from the surrounding earth.{{sfn|Wright|2009|pp=179–180, 188}}

The precise definition of "pendentive" has also been a source of academic contention, such as whether or not corbelling is permitted under the definition and whether or not the lower portions of a [[#Sail dome|sail vault]] should be considered pendentives.{{sfn|Dodge|1984|pp=271–276, 279}} Domes with pendentives can be divided into two kinds: ''simple'' and ''compound''.{{sfn|Catholic}} In the case of the ''simple dome'', the pendentives are part of the same sphere as the dome itself; however, such domes are rare.{{sfn|Fletcher}} In the case of the more common ''compound dome'', the pendentives are part of the surface of a larger sphere below that of the dome itself and form a circular base for either the dome or a drum section.{{sfn|Catholic}}

The fields of [[engineering]] and [[architecture]] have lacked common language for domes, with engineering focused on structural behavior and architecture focused on form and symbolism.{{efn|name=Palmisano definitions 2010}}{{efn|name=Chilton definitions 2000a}}{{efn|name=Mainstone definitions 2000a}}{{efn|name=Chilton definitions 2000b}}{{efn|name=Jannasch definitions 2016}} Additionally, new materials and structural systems in the 20th century have allowed for large dome-shaped structures that deviate from the traditional compressive structural behavior of masonry domes. Popular usage of the term has expanded to mean "almost any long-span roofing system".{{efn|name=Chilton definitions 2000b}}