adversity aversion

the words adverse and averse can cause confusion and are often erroneously interchanged. Both are adjectives with negative meanings, but they are not interchangeable; they are subtly differentiated by interest vs inclination:

• adverse (adj) - unfavorable. used in the "against one's best interest" case. base word for adversity and adversary.
  
• averse (adj) - having repugnance or opposition of mind. used in the "against one's personal inclinations" case. base word for aversion.

these derived words (adversity/aversion) are the best mnemonic for deciding which to use, and have cured me of my bad habit of saying things like "I am not adverse to medicine with no averse effects."