<p><strong>Adjective</strong></p><ul><li>used or engaged in performing operations: an operating surgeon.</li><li>of, for, or pertaining to operations: an operating budget.</li><li>of or relating to the proper operation of a machine, appliance, etc.: a manual of operating instructions.</li><li>Railroads: of, pertaining, or belonging to railroad workers, as engineers or firemen, who are directly engaged in the mechanical operation of trains: an operating union.</li></ul>