This is something that has weirded me out for a while: why is colour described in absolute terms but smell in relative terms? Like, red and green and blue refer to exact sensory inputs (wavelengths of light), not some prototypical "red" thing which we say things that are red look like ("orange" is an outlier). But with smell there's none of that, it's all "smells like banana" and "smells like nail polish remover", there don't seem to be accepted terms for exact smells. There's a similar thing going on with taste, though at least there you have the five primary tastes (sour, sweet, bitter, salty, umami) even if there's some degree of other stuff going on (the enduring popularity of the phrase "tastes like chicken" proves that taste is not just about the five main tastes). Is this just there not being enough good words or are smell and taste (and now that I'm thinking about it, I guess touch) somehow more complex senses than vision is? Personally I find it a lot harder to imagine tasting a taste or smelling a smell than seeing a colour, so I want to propose that it's the latter, but maybe that's just me? Actually, wait a minute-
Somebody needs to write the Wikipedia article for primary odors, please.
(I'm not including sound in this analysis because all the sound names are just onomatopoeia and I have no complaints there, that makes sense.)
We do have some smell words that are detached from comparison – 'pungent' and 'putrid' for example refer to types of smells decoupled from a referent. Another example might be petrichor, which is specifically the earthy smell we associate with groundwater and with rain.
And color words often etymologically come from references to things in that color. 'Orange' as you point out is an obvious example, but there are others. The word 'purple' is thought to come from the Greek 'porphyra', which itself is thought to come from the Phoenician name for the murex snail from which purple dye was extracted. 'Green' probably originally referred to plants before it referred to the color; we still have that in idioms like saying someone is 'green' to mean inexperienced – green like shoots or new growth. But those words have long since detached from those original referents to mean the color itself.
Smell words 'decouple' from references to specific things less often, I think, for a few reasons:
- There are just so many more distinct smells. The human nose can detect millions of compounds, and those group into probably hundreds or thousands of distinct smells.
- A smell as we experience it is not a single phenomenon but a complex combination of phenomena; we rarely, in normal life, smell pure compounds, right? If you smell, say, a strawberry, you're getting dozens of different substances. Like with colors or sounds, those then blend into one another. So 'strawberry scent' is really a dozen different scent phenomena in conjunction. This isn't even getting into how smell has a direction; things smell different if you smell them through your nose than if you smell them through the back of your throat – this is why foods can smell different than they taste, the 'retronasal smell' (ie, tasting with your nose) is almost its own sense.
- Smells are much harder to decouple from the things that carry that smell. If something smells like strawberry, it either contains strawberry, or synthetic scents that are chemically identical to what's in a strawberry. Whereas of course many things in nature are orange, and many different orange pigments exist. Color words are useful because they can group disparate things together; scent words can only sometimes do this for broad groups of smells ('vegetal', 'acrid', 'musty', etc).
- Visual input is systematically privileged in Western culture, so I think people in general have less opportunity to develop a vocabulary around smell. People who work with food or perfume will often have a much denser way of talking about those things, but we don't expect kindergartners to have nearly as sophisticated understanding of smell as we expect them to know colors and shapes.
To bolster that last point, and to further enhance a comment below by @joXn, the empirical data on the cognitive consequences of the use of abstract smell terminology in Jahai are very compelling. Whatever the historical trajectory of the Jahai language, the facility and consistency with which its native speakers identify smells totally blows out of the water that of speakers of languages without an abstract smell vocabulary.
If I'm recalling the literature correctly, 'smell experts' in the industrialized West do have somewhat better smell discrimination than their lay counterparts, but do not have the level of inter-rater reliability displayed by Jahai speakers (as well as having longer reaction times), suggesting that even Western experts only have private and idiosyncratic smell vocabularies, and so can't really benefit from collective cultural reinforcement and feedback.