extrados /ek-strāˈdos/ (architecture)

1. The convex surface of an arch
2. The external curve of the keystone of an arch

• head boys
• head-bummer
• head-butt
• head-butted
• head-butting
• head-butts
• headcase
• headcases
• head-centre
• headchair
• headchairs
• headcheese
• headcheeses
• headcloth
• headcloths
• head cold
• head colds
• head count
• head counts
• head-crash
• head-crashes
• head-down display
• headdress
• headdresses
• headed