Mucous makes me nauseous.
At the sight of this sentence, the hairs on Margot’s neck stood straight up. She pushed the paper back towards her student, Marcus, and, jabbing her finger at the sentence, said “That’s wrong.”
“No it’s not,” he said. “It really makes me sick. Can’t stand to look at other people’s snot.”
“No,” said Margot, feeling vaguely queasy, due more to the grammatical infraction than to the imagery, “you have two incorrect usages in that sentence. Here –” she pointed to Mucous – “you’ve used an adjectival form where you should use a noun. The noun mucus is spelled m-u-c-u-s.”
Marcus scratched out the sentence and rewrote it: Mucus makes me nauseus.
“No,” Margot said, “now you have mucus right but there’s no such word as nauseus without the o. It has to be an adjective.”
“But you said it was wrong!” Marcus protested.
Sigh. “It’s the wrong word there. Nauseous should not be used to mean ‘nauseated'; it means causing, not feeling, nausea. You could write mucus is nauseous.”
Marcus pulled a face. “That’s really gross! That sounds like the mucus is about to puke!”
“But using nauseous to mean ‘feeling sick’ is a mark of an insufficiently educated user,” Margot said primly.
“Try telling that to my mother,” Marcus replied.
“Your mother is paying me to improve your English. If she were paying me to improve hers as well, I would. Now, you could say mucus nauseates me. That avoids the issue altogether.”
“You know,” Marcus said, looking at the paper, “I don’t like that, mucus without the o. I think it looks slipperier and grosser with the o. Also without it it looks too much like my name.”
“Well,” explained Margot with obvious patience, “it’s a noun-adjective distinction. The o before the u makes it an adjective. Like callous and phosphorous.”
“So I could become an adjective if I added an o in my name,” Marcus said. “Marcous. …What’s an adjective?”
Margot paused for a moment to decide exactly when to have the splitting headache she could see in her future. “An adjective,” she said, eyes closed, hand on forehead, “is something that modifies a noun. So you have a callus on your hand, no o, but you exhibit callous indifference with an o.”
“And calloused hands, with an o, right?”
“No, because in that case you’re taking a noun and making it an adjective with the ed. So callus with no o gets the ed to be callused. Likewise, phosphorous with an o means ‘containing phosphorus’ or ‘glowing.'”
“So,” Marcus said, nudging the paper forward, “this is Marcous writing, with an o.”
Margot almost smiled. “Unfortunately, we can’t do that with proper nouns. Names, like yours.”
Marcus pursed his lips. “Nothing wrong with a bit of fun now and then,” he muttered. Pause. “So where do we see mucous with an o? Like ‘I don’t want that Kleenex, it’s all mucous?'”
Margot was about to say something and then realized that what she was about to say was not true. “Em… you could. They might not understand you. The most common place to see mucous with an o is mucous membrane, a membrane in your body that has mucus as an essential part of it. Like the inside of your nose.”
Marcus remembered something. “Or mucous relief.”
“No, in that case it’s mucus with no o because it’s really what’s being relieved – like cough suppressant: cough is a noun, not an adjective. If it were mucous with an o, it would suggest that the relief itself was like mucus, or had mucus in it.”
“I don’t think you’re right about that,” Marcus said.
Margot opened her mouth in astonishment at the impudence and was about to set him right on the likelihood of his knowing better than her. He held up a finger. “Hang on.” He jumped up, went into the bathroom, and reappeared in record time. He was holding a bottle of cough syrup, which proclaimed itself Mucous and Phlegm Relief.
Margot took the bottle in her hand, stared at it, and, trying not to hurl it through the nearest window, trying not to scream, and with an overwhelming sense of betrayal, hyperventilated herself to unconsciouness.
Poor Margot. Hard to blame her when a rule of usage proclaimed by all the dictionaries and taught as revealed truth is wantonly trashed by a very large corporation. But the poor lass didn’t even get to expostulate on the origins of mucus and nauseous; by the time the smelling salts were brought out and she came to with that splitting headache she had seen coming down the street, the hour was over.
Well, mucus isn’t a difficult one; it’s Latin, straight down – spelled the same, with the same meaning. Mucous is from Latin mucosus, which could also mean “slimy”. You may remember a slimy glue called mucilage that you used in rubber-tipped bottles in kindergarten and elementary-school days. That’s also derived ultimately from mucus. (Marcus, for its part, is not related.) You may find something gluey about the [mju] or [miw] at the beginning of mucus, and the [k] may bring to mind the closed and phlegmy velum one gets when one has a cold. You may or may not agree with Marcus that it’s slimier with an o.
Nauseous, for its part, comes (as you may now guess) from nauseosus. Of course, there is no nauseus and never was; the noun is nausea. (Needless to say, Mucus makes me nausea is not good.) As to whether one ought to use nauseous to mean “nauseated”, well, be aware that many people will consider you not merely wrong but grossly ignorant and offensive if you do. People can be so touchy about language. And indeed, Latin nauseosus means “causing nausea” and nauseous has been used to mean the same in English since at least 1628, while it has been used to mean “nauseated” only since the later 19th century – though it was in use by 1618 to mean “inclined to nausea; squeamish”.
Still, meanings shift; there are many words that have changed quite completely in meaning over the centuries. And what a word is used for is, ultimately, what it is used for – we can try to enforce specific meanings, but if everyone ignores them and goes with a different meaning, then the language has shifted, which it does all the time. And nauseous is now used almost exclusively to mean “feeling sick”. It is very commonly preceded by feel, feeling, or felt, as well as by become and became, and may also come with forms of make, as in Today’s word tasting note made me nauseous. Who but the “It is I” crowd would ever say, or expect anyone to understand, Today’s word tasting note was nauseous to mean the same thing?