(algebra, order theory, ring theory) A ring, R, equipped with a partial order, ≤, such that for arbitrary a, b, c ∈ R, if a ≤ b then a + c ≤ b + c, and if, additionally, 0 ≤ c, then both ca ≤ cb and ac ≤ bc.

(of troops etc.) in an arrangement in compact units at close intervals and distances, as for marching and/or drill.

(military) A military unit formed up so as to allow space between its ranks. / (nautical) A naval formation in which ships are four cables'-length (2880 feet) apart.

A book or ledger that lists customer orders, especially orders that have not yet been filled.

A court order requiring an offender who is found not guilty by reason of insanity to be admitted to a psychiatric hospital.

(An order to observe) a (temporary) speed restriction.

(UK, Ireland, military, slang) In a state of mess or chaos.

Teutonic Knights

(mathematics) A partially ordered set. / (mathematics) A totally ordered set.

(finance) An instruction to carry out a trade only if the asset to be traded reaches a certain price during the current trading day.