(computer science) a sequence of instructions that a computer can interpret and execute

a set of instructions inserted into a program that are designed to execute (or `explode') if a particular condition is satisfied; when exploded it may delete or corrupt data, or print a spurious message, or have other harmful effects

a program that appears desirable but actually contains something harmful

a software program capable of reproducing itself and usually capable of causing great harm to files or other programs on the same computer

a software program capable of reproducing itself that can spread from one computer to the next over a network