(physics) A dual version of the Wilson loop in which the electromagnetic potential A is replaced by its electromagnetic dual Aᵐᵃᵍ, where the exterior derivative of A is equal to the Hodge dual of the exterior derivative of Aᵐᵃᵍ.

plural of 't Hooft operator

plural of freight operating company

plural of train operating company

(UK, rail transport) A company that runs freight trains on the national railway network in Great Britain under license from the government.

(UK, rail transport) A company that operates passenger trains on the mainline railway network in Great Britain under franchise or license from the Government.

plural of operating room table

An operating table.

(US) A small business that produces homemade foods and is partially exempt from the regulations governing larger commercial food operations.

plural of cottage food operation