Preorder (disambiguation)

The term preorder may refer to:

In mathematics:
 * Preorder, a reflexive, transitive relation
 * Preorder field, a field of sets structure on a set with preorder
 * Preordered field, a field with a preorder
 * Preordering, a vertex ordering from a tree or other graph traversal; see Depth-first search

In marketing:
 * Pre-order – an order placed for an item which has not yet been released.