Final answer:
A wig is the artificial hair covering that completely conceals the client's hair.
Step-by-step explanation:
The artificial hair covering that completely conceals the client's hair is a wig. A wig is a hairpiece made of synthetic or natural hair that is worn to cover the head or enhance the appearance of hair. It can be used to completely hide the client's natural hair or to change their hairstyle or color. Wigs can be attached to the client's head with adhesives, clips, or by sewing it onto a cap.