The adjectives adverse and averse are related both etymologically and semantically, each having opposition as a central sense. Both come from the Latin root vert- meaning “to turn.” In Latin the word adversus meant “turned toward” and “hostile” and is a direct root of adverse. Averse, on the other hand, emerges from the Latin word aversus, which meant “turned away.”
Today adverse is rarely used to describe people but rather of effects or events, and it usually conveys a sense of hostility or harmfulness: adverse reviews; adverse winds; adverse trends in the economy.
Averse describes people and means “feeling opposed or disinclined.” It often occurs idiomatically with a negative to convey the opposite meaning “willing or agreeable,” and is not interchangeable with adverse in these contexts: We are not averse to holding another meeting. Averse is usually followed by to, and in older use occasionally by from. The related noun is aversion: He has an aversion to pickles.
According to Google’s nGram, the use of averse has been falling consistently since the early 1800s, while adverse has generally risen. Which do you use more often?