WordNet sense 1 (involving or causing danger or risk; liable to hurt or harm):

dangerous, unsafe

WordNet sense 2 (exceedingly harmful):

baneful, pernicious

WordNet sense 3 (injurious to physical or mental health):

noxious

WordNet sense 4 (having a tendency to cause harm):

nocent

WordNet sense 5 (deliberately causing harm or damage):

mischievous

WordNet sense 6 (resulting in suffering or adversity):

ill

WordNet sense 7 ((sometimes followed by `to') causing harm or injury):

damaging, detrimental

WordNet sense 8 (extremely harmful; bringing physical or financial ruin):

catastrophic

WordNet sense 9 (harmful to living things):

deleterious, hurtful, injurious

WordNet sense 10 (capable of harming):

bad

WordNet sense 11 (contrary to your interests or welfare):

adverse, inauspicious, untoward

WordNet sense 12 (not encouraging or approving or pleasing):

unfavorable, unfavourable

WordNet sense 13 (tending to cause great harm):

evil

WordNet sense 14 (constituting a disadvantage):

disadvantageous