The part played by a word depends on the context. You will have no difficulty with, for example, "duck" as a noun and a verb. In "duck soup" you will have no difficulty with a noun acting as an adjective. To be precise, we should not say "In 'She wears such stylish clothes' such is an adverb." You should say "In 'She wears such stylish clothes' such functions an adverb."

Sure, but "duck" is not a great example because I think of "duck" (the bird) as mainly a noun, and the adjective use you give as a very exceptional case that's subordinate to its main usage as a noun. "Duck" could also be a verb, but only with a completely unrelated definition. By contrast, "such" doesn't seem to change its meaning so drastically from case to case, and none of its usages as one part of speech are clearly subordinate or controlling to any of the others.

The noun "duck" comes from OE "ducan" (the verb = to dive > duck(n) = that which dives) and are indeed thus related. I think you are looking at the etymology from the wrong perspective: Adjectives and adverbs were derived from nouns and verbs, and often the same word is an adjective and adverb, e.g. "fast". Language was not "created" with parts of speech - it is us who have given names to the functions of words.

I mean, sure, literally any two words can be "related," if you just trace them back enough centuries to some common British ancestor--or enough millennia to some ur-syllable in ancient Mesopotamia, for that matter. Regardless, this isn't a question about how the feudal serfs in Merrie Olde Englande would have used "such"; it's a question about modern English grammar, usage, and categorization of words.

@RiversMcForge it's a question about modern English grammar, usage, and categorization of words. And I answered that above: The part played by a word depends on the context. and Language was not "created" with parts of speech - it is us who have given names to the functions of words. Verbs became noun; nouns became verbs, verbs became adverbs and adjectives, and adjectives became nouns. It is indeed, "all about history." You are looking at it the wrong way, and seem to be asking why there are holes in a cat's skin exactly where its eyes are." :)

Shoe Greybeard I think that idea of how "non-typical" the word such is in these examples is at the heart of my question. For other words that can pull multiple duty - "The duck flew away", "I ate duck soup", "He had to duck because of the low ceiling" - the word is behaving in a more or less typical way of other nouns/adjectives/verbs, respectively. Such, on the other hand, seems to behave very differently from other adjectives (or whatever) even when it's technically pulling adjective (or whatever) duty. It's like it's in a class of its own.

The chapter Word Categories in The Oxford Dictionary of the Word concludes: Numerous studies have shown that the behaviour of words is so complex and disorderly that it cannot be reduced to the grammatical properties associated with the lexical categories. I think the best we can do with 'quirky' words (ODOTW) is to say, for example: "This word in this particular context has more properties of a prototypical adjective than of a prototypical adverb or any of the other word classes".

@Shoe What's another word equally quirky, that crosses a bunch of categories but fits uncomfortably into any particular one when you look closely? Such is the only one I couldn't easily make fit.

The ODOTW discusses the quirky words "possible" and "go".

I can't think of any sentence containing "possible" or "go" where it would not be very straightforward to classify their part of speech. In a sentence like "It's getting late; as such, we should be going," it's much more difficult to pin down what such is doing there. Is it a thing (noun)? Is it referring to a thing (pronoun)? Is it a description modifier (adjective, adverb)? Ask three different people (or grammarians), you'll get three different answers, and each will likely have persuasive reasons that they're right.

You might want to ask about as such in a new question. This is a better example of the classification problem than the such sentences in your question above.

The word 'galore' is both a postpositive quantifier and an adjective in its only (as far as I am aware) usage. There were pavilions galore. = There were many resplendent pavilions. (You can't say 'There were fatalities galore'.) And if you insist on having a neat classification for everything, you have to decide your classification flowchart (constituency tests) (and be prepared to concede that others have the right to disagree) with say 'painting' in 'Brown's slowly painting the desert was mind-numbingly boring to watch.'

The word worth has been classed as an adjective and a preposition. As I said in a paper on the topic, lightly edited, "If it is a preposition, it must have a homophonous derived noun, as in the worth of the book. On the other hand, if it is an adjective, it must be transitive, since it has a complement (that's worth a lot of money)... Let it stand that no matter what category worth may belong to, it is an atypical example of the category."

@EdwinAshworth I like that example, although strictly speaking, the issue with the sentence "There were fatalities galore" isn't a grammatical one, it's that it strikes an inappropriately gleeful tone for the subject matter. (Sounds like something an online gamer might say.) Also, "galore" strikes me as more of a colloquial expression with a single relatively uncommon use, whereas "such" is way more common, often slightly formal-sounding, and has many different uses.

@JohnLawler I think of "worth" as mostly used noun-wise - "She was a woman who knew her worth" - and "worthy" as the adjective version - "A worthy opponent". I guess I never thought about how it functioned in constructions like "He's worth over $1 billion dollars" but I feel like in that context it's being typically being used, explicitly or implicitly, as one word in a multi-word verb, "to be worth": "jewelry worth $50,000 was taken" is the same as "jewelry, which was worth $50,000, was taken". It's the same as "to be valued at".

@RiversMcForge That's the adjective usage -- it's a predicate adjective, and like all predicate nouns and predicate adjectives, uses the auxiliary be. Oh, and no, it isn't the same as be valued at; the article distinguishes among value, worth, price, and cost, which are all related to the same frames, but have different meanings and grammars. It's a complex system.

One more thing -- as usual, limiting oneself to the Eight Parts Of Speech taught in Anglophone schools is rather like limiting oneself to long division in trying to solve differential equations. Those Eight were invented by the Romans for Latin, not English. They're medieval technology and they don't work for English. There are lots more categories in a language like English than the Romans dreamed of. We get plenty of questions here about "What part of speech is <insert English word>?" The answers are always unsatisfactory for those whose faith is challenged.

@JohnLawler Yeah, I think the Eight Parts of Speech model is more like a "lie-to-children": en.wikipedia.org/wiki/Lie-to-children To make a math analogy, it would be like when you tell younger students, "You can't take the square root of a negative number", and then later on when they're more sophisticated you can teach them about i and complex numbers. Obviously Eight Parts of Speech is a very deliberately crude way of breaking it down, but it's interesting that it can be stretched to more-or-less fit over so many words, and only "such" blatantly strains the categories.

They work quite well for Latin, which has markers that indicate which words are which kind, and specifies what endings and stuff go on them. English has practically no endings, and they don't apply to only one class of word (plus English has adjectives, whereas Latin grammarians didn't notice them since they always look like nouns). English open-class words (noun, verb, adjective) can be almost any part of speech, and often are. So knowing what part of speech a given English word is in a given English sentence isn't worth nearly as much as it is for Latin. The little words are the grammar.

You asked for another word that "crosses a bunch of categories but fits uncomfortably into any particular one". How about fun? Examples: "She isn't much fun. / It's no fun being locked down. / It's more fun to be with her than with him. / We had a fun time. / That sounds like fun. / Baking is fun."

The issue with galore concerns parts of speech. Quantifiers do not inform about states of glee, frivolity, informality. That is an adjectival function when modifying a noun. 'Galore' is dual-function.

@EdwinAshworth I would interpret that "adjectival function" as a connotation, rather than the denotation, of "galore", myself--the tone a word conveys to the listener can be quite different from its literal meaning, or grammatical function. But perhaps that distinction is no longer in fashion among English scholars these days :)

Perhaps you'd better look at a reasonable sample of discussions involving connotation, including estimates of strength, and subjectivity, here on ELU. // The thing here is that everyone who is cognisant with the term associates 'galore' with a happy/gay/splendid bounty, rather than a surfeit of dead and wounded. 'There were banners galore' means something more than 'There were a lot of banners'.

I wouldn’t put words in “everybody’s” mouth so confidently on that one, and the dictionary definitions—the denotations —I’ve found only say that “galore” means “in abundance”, which is neutral, since bad things can be present in abundance, too. My personal understanding of “galore”’s connotation has always been that the abundance referred to is so great that it seems faintly absurd, excessive, or over-the-top, like the usage in this link: “guns and copters galore.” robertchristgau.com/get_album.php?id=4556

Here's another good example of "galore" being used to signify "a ridiculous abundance" in this op-ed headline from the New York Times: "Messages Galore, but No Time To Think." nytimes.com/2013/06/16/jobs/… As the author makes clear, in sentences like "people constantly complain that their e-mail in-boxes are unmanageable," they do not consider the abundance of these messages "a happy, gay, or splendid bounty."