Deleterious: Having bad effects
Sentence: Smoking and vaping have deleterious effects.
This word is often found in medical texts, and it is synonymous with the word "harmful." Anything that has bad side effects like medicines or actions can be described as having deleterious effects. Saying "Though chemotherapy is useful, it often has harmful effects." is just as correct as saying "Though chemotherapy is useful, it often has deleterious effects." However, the latter sounds better, smarter, and more dramatic in a way.
Add this word to your daily vocabulary, and watch the heads turn in science class.
Until next week...
Stay Curious ;)