operation (n.)

late 14c., "action, performance, work," also "the performance of some science or art," from Old French operacion "operation, working, proceedings," from Latin operationem (nominative operatio) "a working, operation," noun of action from past-participle stem of operari "to work, labor" (in Late Latin "to have effect, be active, cause"), from opera "work, effort," related to opus (genitive operis) "a work" (from PIE root *op- "to work, produce in abundance").

The surgical sense of "act or series of acts performed upon a patient's body," usually with instruments, is first attested 1590s. The military sense of "act of carrying out a preconcerted series of movements" is by 1749.

Definitions of operation

operation (n.)
the state of being in effect or being operative;
that rule is no longer in operation
operation (n.)
a business especially one run on a large scale;
a multinational operation
a large-scale farming operation
they had to consolidate their operations
they paid taxes on every stage of the operation
operation (n.)
a planned activity involving many people performing various actions;
they organized a rescue operation
the biggest police operation in French history
consolidate the companies various operations
running a restaurant is quite an operation
operation (n.)
(computer science) data processing in which the result is completely specified by a rule (especially the processing that results from a single instruction);
it can perform millions of operations per second
operation (n.)
activity by a military or naval force (as a maneuver or campaign);
it was a joint operation of the navy and air force
Synonyms: military operation
operation (n.)
a medical procedure involving an incision with instruments; performed to repair damage or arrest disease in a living body;
they will schedule the operation as soon as an operating room is available
Synonyms: surgery / surgical operation / surgical procedure / surgical process
operation (n.)
a process or series of acts especially of a practical or mechanical nature involved in a particular form of work;
certain machine tool operations
the operations in building a house
Synonyms: procedure
operation (n.)
process or manner of functioning or operating;
the power of its engine determines its operation
the plane's operation in high winds
Synonyms: functioning / performance
operation (n.)
(psychology) the performance of some composite cognitive activity; an operation that affects mental contents;
the cognitive operation of remembering
Synonyms: process / cognitive process / mental process / cognitive operation
operation (n.)
(mathematics) calculation by mathematical methods;
they were learning the basic operations of arithmetic
Synonyms: mathematical process / mathematical operation
operation (n.)
the activity of operating something (a machine or business etc.);
her smooth operation of the vehicle gave us a surprisingly comfortable ride