(law, chiefly US) An ordinance issued on the authority of the head of the executive branch of government.

(set theory, order theory) A partial order, ≤, (a binary relation that is reflexive, antisymmetric, and transitive) on some set S, such that any two elements of S are comparable (for any x, y ∈ S, either x ≤ y or y ≤ x).

To buy or sell goods to be delivered by mail

(especially of machinery) The state or condition of being operational or of functioning acceptably.

plural of ordered pair

(Britain) An official order forbidding press or broadcast discussion of a specified subject; a public interest immunity certificate.

(cricket) The batsmen, constituting the tail, who bat last - roughly in positions 8 to 11.

(taxonomy) A taxonomic category below suborder and above superfamily.

(cricket, baseball, softball) The sequence in which a side's batsmen go in to bat.

Used other than figuratively or idiomatically: see doctor, -'s, orders. / (Britain, bingo) The number nine.