not elaborate or artificial; plain: a simple style. not ornate or luxurious; unadorned: a simple gown. unaffected; unassuming; modest: a simple manner. not complicated: a simple design.

What is plain design?

A plain object, surface, or fabric is entirely in one colour and has no pattern, design, or writing on it.

What is a simple product design?

The definition of product design describes the process of imagining, creating, and iterating products that solve users’ problems or address specific needs in a given market. The key to successful product design is understanding the end-user customer, the person for whom the product is being created.