n.
Pronunciation: ' ek-str ə - ˌ däs, - ˌ d ō ; ek- ' str ā - ˌ däs
Function: noun
Inflected Form: plural -dos · es \ - ˌ dä-s ə z \ or -dos \ - ˌ d ō z, - ˌ däs \
Etymology: French, from Latin extra + French dos back ― more at DOSSIER
Date: 1772
: the exterior curve of an arch ― see ARCH illustration