In woodworking, this term describes a particular grain pattern on flatsawn boards. As the drawing shows, the center of the board exhibits prominent arch-shaped grain lines -- pointed arches that nest inside one another -- that some claim resemble the pointed arches of the exteriors of Gothic cathedrals.
To the woodworker,
"Trees are nature's cathedrals, places for worship of natural beauty". In their natural state, however, while definitely 'cathedral-like', trees are open to life, and death, and in 'death' reemerge in some other form, perhaps equally beautiful.
Sources: Woodworking Magazine No 13 Spring 2009, page 29; illustration by Robert W. Lang