Sweet, sharp, tangy, tart: language is delicious! So in a week that’ll surely end in a rash of Thanksgiving-related food comas for many of us (if not tears and recriminations), it’s probably about time to give thanks to the practically edible words that make food tasty (so sweet and so cold). Oddly enough, sometimes those very same words that give a bit of nuanced umami to our sense of taste can also be used for some of our other senses, creating a poignant, shared language. Warm, bright, crisp, soft… these are some of the words that could each describe aspects of smell, sound, sight or touch, as well as taste, all without batting an eyelid. We can speak of warm hands (touch), warm lights (sight), warm voices (sound) out in the crisp autumn air (touch, smell), like a crisp wine (taste), just to give a crisp answer (sound).

So we can use the same words to describe different senses—why would this be weird or noteworthy? After all, many words can acquire new meanings and nuances over time, especially through metaphorical use. Obviously we mostly have adjectives to thank for this, but it turns out not all adjectives are created equal. Some are more footloose and fancy-free than others and can be found lingering and malingering in more linguistic contexts than you might expect.

According to Bodo Winter, some adjectives such as “large” or “beige” seem fairly neutral, cognitively speaking, while others, such as “pungent,” “fragrant” or “delicious” carry a much stronger emotional sense. Recent research, for example, has found that tempting and attractive food words actually trigger cognitive simulations of eating that food far more than more neutral words about food.

Winter points out that adjectives that originally pertain to taste and smell are “emotionally flexible” and occur in more contexts than more neutral adjectives (such as the aforementioned poor, unloved beige). Researchers have found that taste is closely and cognitively tied to the human reward system and shares brain space with how we process emotions. Likewise, there’s a very strong connection between our memories of smells, odors, fragrances, and our feeling for nostalgia. Turns out the musty past can be a pretty smelly place. So the sense words we choose to use in certain linguistic contexts can trigger certain neural responses. Meanwhile “beige smells” or “beige sounds” might be possible in poetry (you never can tell with poets), but out of context we don’t have a strong, consistent concept of what that can mean.

Joseph M. Williams describes this class of emotionally flexible adjectives as “synesthetic” and this is where this gets interesting. Synesthesia is a relatively rare cognitive phenomenon where certain kinds of stimuli might trigger (usually) involuntary sensations that are more commonly experienced through another sense or modality. For example certain words or sounds might trigger certain food tastes in the mouth, or induce a feeling of being touched. Does that sound (or taste) a little mixed up? In fact, synesthetic abilities give some language savants an edge, while other synesthetes are able to develop their unique sense of creativity thanks to this richer neurological access to multiple senses in parallel.

If you’re the tiniest bit jealous of a synesthete’s heightened sensibilities and multi-layered understanding of the world, worry not! To a certain extent, perhaps without realizing it, by using synesthetic adjectives (or metaphors) we’re all experiencing a kind of synesthetic behavior that is doing something in our brains. It’s unremarkable to us to describe taste as being sweet, because sweetness is ordinarily a property of taste, but how do we conceptualize touch as being sweet or a voice or music as sounding sweet? What about a sweet smell or fragrance? Yet we’re all able to understand and have a feeling about what “sweet” could mean in those different linguistic contexts, all while linking back to the original primary meaning.

What’s more, William’s study shows that there’s a consistency to how languages change the semantics of synesthetic words for use with different senses. For example, “cloying,” a word we might use to describe the strange seasonal concoction of sweet potatoes mashed with melted marshmallow (which, as a non-American, I was always given to understand is a required traditional Thanksgiving dish going way back to Pilgrim times), actually started out as a word describing something to do with touch, meaning to choke or to clog. It semantically shifted to describe a kind of taste (overly sweet) before taking on a more general figurative meaning that could apply to sound (his cloying voice). Similarly “bitter” originally had a more physical tactile meaning, related to “bite,” meaning “sharp” or “cutting.” Now, of course, we speak more easily of “bitter foods” and “bitter arguments.”

These semantic shifts are often initially prompted by metaphorical uses of words at first, but this is not a case of metaphor haphazardly wreaking havoc on meaning. It’s interesting to see not only how the semantics of these synesthetic adjectives change, but what doesn’t and seemingly can’t change. Can we ever meaningfully speak of “loud heights” or “salty hugs“? According to Williams, while touch adjectives might transfer to taste or sound, taste adjectives don’t tend to transfer to touch, but might sometimes change to smell (sour smells) and sound (dulcet music). Williams offers evidence to suggest this kind of semantic shift might be generally consistent across other languages as well, such as in Japanese. A word like “atatakai” (warm) can shift from touch to color to sound.

Interestingly, for olfactory adjectives, Williams finds that there are not many that start out primarily as smell words that transfer in meaning at all. Why would this be? In fact, despite the importance of our sense of smell, which is so closely linked to our emotional sense of nostalgia and memory, it appears we don’t have the words at all—it seems we’re really bad at naming smells. We tend to use words from other senses or more often words that remind us of other smells (e.g. it smells smoky/citrus-y/like a rose/like a wet dog) and don’t have many words that deal with properties of smells. Compared with the rich vocabulary we have for tactile, gustatory, auditory, and visual senses, the dearth of smelly adjectives seems rather odd, doesn’t it?

It’s not clear whether this is an interesting fact about English or a more universal trend. For some researchers, the difficulty in naming scents and smells, at least in English, has to do with the rudimentary olfactory information which is being passed onto lexical centers, which is relatively less nuanced than auditory or visual signals. Reusing the properties of other senses might help us reach an understanding of how to process smells in a less crude way than “good” or “bad” smells. Conversely, there’s evidence from other languages that suggests some other cultures, such as in Maniq, may experience the world through the lens of more nuanced olfactory senses than we do in English, and have the robust lexical toolbox to describe it, in the same way we can consistently define gradations of other senses, such as touch and taste.

Clearly, there’s more work to be done to uncover the mysteries behind our spidey senses and how we talk about them. The language we use to describe our senses is not just a matter of finding the right words. It also reveals how we tend to understand and receive the world around us, primarily through some senses and perhaps not others. Synesthetic adjectives show how we connect and translate what we experience in the world, through delicious, fragrant, brilliant, vivid, poignant semantic change, into a richer shared language for all our senses.