Several days ago, the Twitter account for the Chicago Manual of Style tweeted, “If you’re feeling sick, use nauseated rather than nauseous. Despite common usage, whatever is nauseous induces nausea.” The relevant entry in Chicago reads,
Whatever is nauseous induces a feeling of nausea—it makes us feel sick to our stomachs. To feel sick is to be nauseated. The use of nauseous to mean nauseated may be too common to be called error anymore, but strictly speaking it is poor usage. Because of the ambiguity of nauseous, the wisest course may be to stick to the participial adjectives nauseated and nauseating.
Though it seems like a straightforward usage tip, it’s based on some dubious motives and one rather strange assumption about language. It’s true that nauseous once meant causing nausea and that it has more recently acquired the sense of having nausea, but causing nausea wasn’t even the word’s original meaning in English. The word was first recorded in the early 17th century in the sense of inclined to nausea or squeamish. So you were nauseous not if you felt sick at the moment but if you had a sensitive stomach. This sense became obsolete in the late 17th century, supplanted by the causing nausea sense. The latter sense is the one that purists cling to, but it too is going obsolete.
I searched for nauseous in the Corpus of Contemporary American English and looked at the first 100 hits. Of those 100 hits, only one was used in the sense of causing nausea: “the nauseous tints and tinges of corruption.” The rest were all clearly used in the sense of having nausea—“I was nauseous” and “it might make you feel a little nauseous” and so on. Context is key: when nauseous is used with people, it means that they feel sick, but when it’s used with things, it means they’re sickening. And anyway, if nauseous is ambiguous, then every word with multiple meanings is ambiguous, including the word word, which has eleven main definitions as a noun in Merriam-Webster’s Collegiate. So where’s this ambiguity that Chicago warns of?
The answer is that there really isn’t any. In this case it’s nothing more than a red herring. Perhaps it’s possible to concoct a sentence that, lacking sufficient context, is truly ambiguous. But the corpus search shows that it just isn’t a problem, and thus fear of ambiguity can’t be the real reason for avoiding nauseous. Warnings of ambiguity are often used not to call attention to a real problem but to signal that a word has at least two senses or uses and that the author does not like one of them. Bryan Garner (the author of the above entry from Chicago), in his Modern American Usage, frequently warns of such “skunked” words and usually recommends avoiding them altogether. This may seem like sensible advice, but it seems to me to be motivated by a sense of jealousy—if the word can’t mean what the advice-giver wants it to mean, then no one can use it.
But the truly strange assumption is that words have meaning that is somehow independent of their usage. If 99 percent of the population uses nauseous in the sense of having nausea, then who’s to say that they’re wrong? Who has the authority to declare this sense “poor usage”? And yet Garner says, rather unequivocally, “Whatever is nauseous induces a feeling of nausea.” How does he know this is what nauseous means? It’s not as if there is some platonic form of words, some objective true meaning from which a word must never stray. After all, language changes, and an earlier form is not necessarily better or truer than a newer one. As Merriam-Webster editor Kory Stamper recently pointed out on Twitter, stew once meant “whorehouse”, and this sense dates to the 1300s. The food sense arose four hundred years later, in the 1700s. Is this poor usage because it’s a relative upstart supplanting an older established sense? Of course not.
People stopped using nauseous to mean “inclined to nausea” several hundred years ago, and so it no longer means that. Similarly, most people no longer use nauseous to mean “causing nausea”, and so that meaning is waning. In another hundred years, it may be gone altogether. For now, it hangs on, but this doesn’t mean that the newer and overwhelmingly more common sense is poor usage. The new sense is only poor usage inasmuch as someone says it is. In other words, it all comes down to someone’s opinion. As I’ve said before, pronouncements on usage that are based simply on someone’s opinion are ultimately unreliable, and any standard that doesn’t take into account near-universal usage by educated speakers in edited writing is doomed to irrelevance.
So go ahead and use nauseous. The “having nausea” sense is now thoroughly established, and it seems silly to avoid a perfectly good word just because a few peevers dislike it. Even if you stick to the more traditional “causing nausea” sense, you’re unlikely to confuse anyone, because context will make the meaning clear. Just be careful about people who make unsupported claims about language.