Operation may refer to:

• Surgery, a medical specialty that treats diseases or injuries by operative manual and instrumental treatment.
• An operation or operator in mathematics. See unary operation, binary operation, arity.
• In language, an operation is a word which represents a function (or instruction) rather than a term, or a name.
• In computer science, an operation is called an instruction.
• Military operation, a military action (usually in a military campaign) using deployed forces.
• Covert operation, a military or political action that is both clandestine and denied by the government undertaking the action.
• Sting operation, an operation designed to catch a person committing a crime by means of deception.
• Business operations, manufacturing operations, operations management.
• Operation of law, a legal term that indicates that a right or liability has been created for a part.
• Anomalous operation, in parapsychology, a term describing a broad category of purported paranormal effects.
• Musical operations such as transposition, inversion, multiplication, permutation, counterpoint.
• Operation (game), a battery-operated game of physical skill.

Operation | Operación | Operacio | Opération | Operación | 手術 | Operacja | Операция | Operacija | Operation | 运算