Its a word used in assamese meaning ; To make someone accept his/her defeat or loss in any circumstance. But this is derived from the hindi word "man" meaning accept, " da " as from english "the" , and again "har" meaning defeat. So Mandahar
E be set sala mandahar be, mandahar! ; Hey dude accept your defeat man, accept.
by chootmeinbhoot December 31, 2010