(n) The act of executing something. The state of being executed. The manner, style, or result of performance: The plan was sound; its execution, faulty. The act or an instance of putting to death or being put to death as a lawful penalty. The act of beginning and carrying through to completion: discharge, effectuation, performance, prosecution. See do/not do. One's artistic conception as shown by the way in which something such as a dramatic role or musical composition is rendered: interpretation, performance, reading, realization, rendering, rendition. See performing arts.

Business Law: the signing, sealing, and delivering of a contract or agreement making it valid. The carrying into effect of a court judgment. A writ empowering an officer to enforce a judgment. Validation of a legal document by the performance of all necessary formalities. Computer and Software Engineering: process by which a computer or a virtual machine carries out the instructions of a computer program.

Criminal Law: Capital punishment. The carrying out of some act or course of conduct to its completion. In criminal law, the carrying out of a death sentence.
Investment: The completion of a buy or sell order for a security. Investopedia Says: Brokers are required by law to give investors the best execution possible. “Understanding Order Execution: Often investors and traders alike do not fully understand what happens when you click the "enter" button on your online trading account. If you think your order
is always filled immediately after you click the button in your account, you are mistaken. In fact, you might be surprised at the variety of possible ways in which an order can be filled and the associated time delays. How and where your order is executed can affect the cost of your transaction and the price you pay for the stock. “
Securities: carrying out a trade. A broker who buys or sells shares is said to have executed an order.

Definition: carrying out of a task / Antonyms: abandoning, disregard, failure, forgetting, ignorance, leaving, neglect
Definition: killing / Antonyms: birth
Archaic: Effective, punitive, or destructive action.
Malexecution = bad execution
Source: Answers.com