NOHREF indicates that the <AREA ...> is not a link.
Of course, NOHREF doesn't make much sense unless the area is in a map that uses <AREA SHAPE=DEFAULT> or the area overlies another area that does have an HREF. For example, suppose we wanted an image map in which a circle in the map is a link, but a smaller circle inside the link circle is not a link. We could accomplish that by first putting the tag for the inner area (earlier <AREA ...> tags overlay later <AREA ...> tags), and using the NOHREF atribute, then putting the tag for the outer <AREA ...>: