The act, practice, or profession of instructing: math instruction. Imparted knowledge: We sought further instruction in a more advanced class. An imparted or acquired item of knowledge: The judge gave the jury an instruction in how the law defines an accomplice. often An authoritative direction to be obeyed; an order: had instructions to be home by midnight. Detailed directions about how to do something: read the instructions for assembly. Computers A sequence of bits that tells a central processing unit to perform a particular operation and can contain data to be used in the operation.