<unk>  is the loss of hair that is caused by rubbing of the hair, follicles, or skin around the follicle. The most typical example of this is the loss of ankle hair among people who wear socks constantly for years. The hair may not grow back even years after the source of friction has ended.
Frictional alopecia
Triangular alopecia
Traction alopecia
Hot comb alopecia
Pressure alopecia
Hypertrichosis cubiti
Central centrifugal cicatricial alopecia
Onychogryphosis