In colloquial usage, a lattice is a structure of crossed laths with open spaces left between them. The term is used in various technical senses, all of which have some geometrical relation to the dictionary definition.
This concept is used in materials science, in which a lattice is a 3-dimensional array of regularly spaced points coinciding with the atom or molecule positions in a crystal.
It also occurs in computational physics, in which a lattice is an n-dimensional geometrical structure of sites, connected by bonds, which represent positions which may be occupied by atoms, molecules, electrons, spins, etc. For an article dealing with the formal representation of such structures see Lattice Geometries. Different types of lattice models are used in physics, mathematics, and finance.
In baking, various pastries and pies can be made with a lattice pattern, and special cutters are available to facilitate the creation of such patterns.