"Filled triangle" is a term from the game of
Go (
Wei Qi/
Badouk) and refers to the shape of stones formed by White (0) below. Black is shown by (X):
......
..00..
..X0..
......
Note that this is similar to the empty triangle, but with an opponent's stone inside the triangle. Unlike the empty triangle, though, the filled triangle is a good shape, because it puts a pressure on the opponent's stone and provides a lot of thickness.