I've been taught that if I feel like I'm going to throw up, then I'm feeling nauseated. I was also taught that saying "I'm feeling nauseous" is incorrect as nauseous actually means "causing nausea or disgust". In other words, nauseous was best used in sentences like:
- The nauseous fumes from the bus caused the people waiting at the best stop to scatter.
- It's best to boil the kimchi in the soup stock longer if you know your guests are sensitive to its nauseous flavour.
Because English is such a living and dynamic language, the usage of nauseated and the definition of nauseous have been changing rapidly. This is both amazing and frustrating at the same time as it means users of English need to constantly update their knowledge of English. Nauseated still means "to be affected by nausea" but you rarely hear people saying, "I feel nauseated" these days. Instead, you hear people saying, "I feel nauseous." As much as people like me who have learnt the "old" usage would like to keep to that, sometimes we just have to move with the times. That's not to say we can't say "I feel nauseated" anymore, it's just that it's now acceptable to say, "I feel nauseous."
And what about the original meaning of nauseous which is "causing nausea or disgust"? That definition appears to be slowly transferring over to nauseating. So for the two examples above, it's no longer wrong to replace nauseous with nauseating. Although, truth be told, that makes me a little nauseated.
