Is there a word for "Supercomponent", similar to "Subcomponent", but in the other direction?

Solution 1:

In manufacturing, components are combined to create an assembly. You will see this word on parts diagrams and other documentation about how to construct a machine. In fact, a component is an assembly of its subcomponents. For example, most cars have what is called a "tail light assembly" which consists of a light bulb, socket, reflector, and lens. The "seat" in your list would be ordered from a supplier as a "seat assembly" to distinguish it from the "seat frame".

However, there is a conceptual problem with your question: although the tail light is part of a car, a car is a lot more than something that has a tail light. In manufacturing, you might call the car a product or a machine.

For your list, I would use used in or part of

Seat has subcomponents:
- Fabric
- Cushion
- Frame

Seat is used in:
- Car
- Desk
- Airplane

Or just say a seat is a subcomponent of a car.

Edit: On further reflection, I like my second answer better:

Seat has subcomponents:
- Fabric
- Cushion
- Frame

Seat is a subcomponent of:
- Car
- Desk
- Airplane