One semester of English Usage long ago has led to my constant analysis of usage of the English language. We had to memorize lists of misused words and what the correct usage should have been. Among the words ... nauseated versus nauseous. This confession nearly carbon dates me, but here is how things stacked up for nauseated and nauseous in 1981:
Nauseous meant, to cause nausea or disgust.
Nauseated meant, to be affected with nausea or disgust.
More recently, it is common to hear "I am nauseous." Hearing this was like nails scraping a chalkboard. Gong. A big red circle with a line through it. No no no!!! You are NOT nauseous. Or ... well maybe you are nauseous.
The dictionary entry for these two words indicates that common misusage is winning out. We can use the same word, nauseous, interchangeably for both cause and effect. I might as well throw my 30 year old college textbook away, and I promise to learn to think of nauseous in its previously misused, now acceptable form. To think otherwise would constitute erroneous usage snobbery which is far worse than usage snobbery.
So next time someone says they are nauseous, I will cease being nauseated by their presence and ask them if they'd like a Pepto Bismol.