"Aggravate" means to make a situation worse or more severe. The opposite of this is "alleviate," which means to make a situation better or less severe.
- "Affront" means an insult or offense, which is not the opposite of aggravate.
- "Abbreviate" means to shorten, which is unrelated to the meaning of aggravate.
- "Irritate" means to make someone annoyed or angry, which is similar in meaning to aggravate, not the opposite.
Thus, the correct antonym of "aggravate" is "alleviate."