Final answer:
A small wig used to cover the top or crown of the head is called a hairpiece or toupee. These are used to cosmetically enhance the appearance of one's hair in areas of thinning or hair loss.
Step-by-step explanation:
A small wig used to cover the top or crown of the head only is referred to as a hairpiece or toupee. These terms describe a partial wig that can be used for various purposes, including cosmetic, fashion, or to cover hair loss. Hairpieces and toupees are designed to blend in with the wearer's natural hair and can be attached in different ways, such as with clips, glue, or tape. The primary function is to enhance the appearance of hair where it may be thinning or missing.