from The American Heritage® Dictionary of the English Language, 4th Edition
- n. The upper or exterior curve of an arch.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. The outer or upper curve of an arch.
from the GNU version of the Collaborative International Dictionary of English
- n. The exterior curve of an arch; esp., the upper curved face of the whole body of voussoirs. See intrados.
from The Century Dictionary and Cyclopedia
- n. The upper or convex surface of an arch or of a vault.
- n. The outer curve of a voussoir. See arch, 2.
- n. In mech., the locus of the lower ends of wires, of uniform weight per unit of length, hanging down from points on a cord which is perfectly flexible, inextensible, and without weight. When the wires are equally distant from one another and of equal length, the extrados is a parabola.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. the exterior curve of an arch
French : Latin extrā, outside; see extra- + French dos, back (from Latin dorsum).(American Heritage® Dictionary of the English Language, Fourth Edition)
From French, from Latin extra ("outside") + French dos ("back") (from Latin dostrum). (Wiktionary)