stand-alone
noun
Definitions
A device that can operate on its own, rather than as an accessory for another device.
(by extension) Something that is not a part of some series or sequence.
adjective
Definitions
Operating, functioning, or existing without additions or assistance; independent; able to be separate or separated.
Example: They offer an inexpensive add-on for a computer, or a stand-alone system with all the functions built in.