Definition from Wiktionary, the free dictionary
See also: pre-order
to order in advance
preorder (plural preorders)
- An order for goods or services placed in advance.
- (set theory) A binary relation that is reflexive and transitive.
- The relation of logical implication over sentences is an example of a preorder.
preorder (not comparable)
- (computing theory) Of a tree traversal, recursively visiting the root before the left and right subtrees.