Today's Word of the Day means...
a saying to ward off bad luck or invite good luck; also called touch wood
old Irish belief that knocking on wood lets spirits know you thank them
The thick xylem of trees and shrubs, resulting from secondary growth by the vascular cambium, which produces new layers of living xylem. The accumulated living xylem is the sapwood. The older, dead xylem in the interior of the tree forms the heartwood. Often each cycle of growth of new wood is evident as a growth ring. The main components of wood are cellulose and lignin.
Some people say, “Knock on wood,” and then knock on something made of wood for good luck, when they have made a remark that has been true up to that point and they want it to continue to be true: “I've never had an accident yet, knock on wood.”
Note: The expression alludes to an ancient superstition that touching wood would ward off evil spirits.
[1970s+ Black; fr a shortening of peckerwood]