WordNet sense 1 (process or manner of functioning or operating):

performance, functioning

WordNet sense 2 ((psychology) the performance of some composite cognitive activity; an operation that affects mental contents):

process, process, cognitive operation, cognitive process, mental process

WordNet sense 3 (activity by a military or naval force (as a maneuver or campaign)):

military operation

WordNet sense 4 ((mathematics) calculation by mathematical methods):

mathematical process, mathematical operation

WordNet sense 5 (a medical procedure involving an incision with instruments; performed to repair damage or arrest disease in a living body):

surgery, surgical operation, surgical procedure, surgical process

WordNet sense 6 (a process or series of acts especially of a practical or mechanical nature involved in a particular form of work):

procedure