adjective

causing great damage.

a disastrous fire swept through the museum

catastrophic,calamitous,cataclysmic,tragic,devastating,ravaging,ruinous,harmful,injurious,detrimental,adverse,dire,terrible,awful,shocking,appalling,dreadful,grievous,horrible,black,dark,bad,unfortunate,unlucky,ill-fated,ill-starred,inauspicious,unfavourable