(radio) An electromagnetic wave refracted back to the Earth by the ionosphere.
vandyke
vandyke
noun
A style of dress or collar similar to those in Anthony van Dyck's portrait paintings; a small round cape, the border ornamented with points and indentations.
A style of facial hair which has both a mustache and goatee but with all cheek hair shaven.
An edge with ornamental triangular points.
verb
(transitive) To fit or furnish with a vandyke; to form with points or scallops like a vandyke.