It's illegal for them to use the term, for several different reasons.
The Navajo tribe suing Urban Outfitters for trademark violations
Urban Outfitters Mesh Panties
Urban Outfitters settles with Navajo Nation after illegally using tribe's name, Native Americans
Urban Outfitters under fire from Native Americans over 'illegal' misuse of ' Navajo' description on fashion items
2 counts dismissed in Navajo case against Urban Outfitters
Backlashes - The Cut
Urban Outfitters under fire from Native Americans over 'illegal' misuse of ' Navajo' description on fashion items
Urban Outfitters product 'reminiscent' of Holocaust?
Urban Outfitters is no stranger to controversies over its fashion and product lines
Forever 21 Is in Trouble for Making 'Navajo' Panties, Too
Urban Outfitters Sued Over 'Navajo' Panties - FindLaw
Urban Outfitters Controversies
Urban Outfitters Under Fire Again: This Time From the Navajo Nation - Racked LA
Urban Outfitters gets two counts of Navajo Nation lawsuit dismissed
Victoria's Secret apologizes for use of headdress