A lattice is a decorative wooden frame or fence. Your grandmother's prize garden might include a lattice covered in bright pink roses.
An ornamental design — made usually of wood — that you might see on the porch of a house or a garden trellis, is a lattice. Lattice is often made of a criss-crossed, diamond pattern of wood or metal slats. Lattice is a nice material for a porch because it lets in air and light but still gives privacy. You can also call something that resembles such a pattern lattice, like lattice wallpaper, or a lattice-patterned silver necklace.