Flatland is a two-dimensional world populated by geometric figures, first described in the 1884 novella of the same name by Edwin Abbott Abbott. The term 'Flatland' can also be used to refer to any two-dimensional universe. The crossword solution for Flatland is MESA, which is a Spanish word meaning 'TABLE' or 'PLATEAU'. It is an appropriate term for Flatland, as the characters in the novella live on a flat surface.