(computing theory, of a traversal of a tree) Such that, recursively, the root is visited before the left and right subtrees.

(transitive) To order (goods or services) in advance, before they are available. / (transitive) To sort or arrange beforehand.

An order for goods or services placed in advance. / (set theory, order theory) A binary relation that is reflexive and transitive.

simple past tense and past participle of preorder

(set theory, order theory, of a set) Equipped with a preorder.

present participle of preorder

plural of preorder