An instruction is defined as:

instruction

NOUN: 3. Computer Science 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. 4a. An authoritative direction to be obeyed; an order. Often used in the plural: had instructions to be home by midnight. b. instructions Detailed directions on procedure: read the instructions for assembly. OTHER FORMS: in·struction·al —ADJECTIVE

The American Heritage® Dictionary of the English Language: Fourth Edition. 2000. http://www.bartleby.com/61/10/I0171000.html