'Extrados' definitions:

Definition of 'extrados'

(from WordNet)
noun
The exterior curve of an arch

Definition of 'Extrados'

From: GCIDE
  • Extrados \Ex*tra"dos\, n. [F.; pref. extra- outside + dos (L. dorsum) the back.] (Arch.) The exterior curve of an arch; esp., the upper curved face of the whole body of voussoirs. See Intrados. [1913 Webster]