| foolhardy |
| foul(adjective, wicked) |
| frightening |
| grave(adjective, dangerous, crucial) |
| inflammable(adjective, ready) |
| injurious(adjective, harmful, dangerous, detrimental) |
| insubstantial(unstable, vulnerable, dangerous, unprotected, precarious) |
| mean(adjective, delicate, sensitive, wicked, tricky) |
| nefarious(adjective, wicked, harmful, injurious, detrimental) |
| negative(harmful, injurious, detrimental) |
| noxious(adjective, harmful, dangerous, injurious, detrimental) |
| on thin ice(expression, adjective, idiom, delicate, uncertain) |
| perverse(adjective, wicked, harmful, injurious, detrimental) |
| poisonous(adjective, harmful, dangerous, injurious, detrimental) |
| pressing(adjective, bad, heavy, significant, serious) |
| reckless |
| serious(adjective, bad, severe, heavy, significant) |
| suspect(uncertain, shaky, unclear, unlikely, questionable) |
| terrible(adjective, wicked, dangerous) |
| terrifying(adjective, dangerous) |