A quantity to which an operator is applied (in , the operands of the subtraction operator are 3 and ).
(computing) A mnemonic used to refer to a microprocessor instruction in assembly language.
The symbol, quantity, or thing upon which a mathematical operation is performed; - called also faciend.
2010 and the .NET 4 Platform (page 655)
a quantity upon which a mathematical operation is performed
In computing, an opcode (abbreviated from operation code, also known as instruction machine code, instruction code, instruction syllable, instruction parcel or opstring) is the portion of a machine language instruction that specifies the operation to be performed. Beside the opcode itself, most instructions also specify the data they will process, in the form of operands.
In mathematics an operand is the object of a mathematical operation, i.e., it is the object or quantity that is operated on.