/ ˈhɑːmfl; NAmE ˈhɑːrmfl/ adjective
harmful (to sb/sth) causing damage or injury to sb/sth, especially to a person's health or to the environment :
the harmful effects of alcohol
Fruit juices can be harmful to children's teeth.
the sun's harmful ultra-violet rays
Many household products are potentially harmful.
► harm·fully /-fəli/ adverb harm·ful·ness noun [ U ]