Reader Valerio (an old friend with an exploring mind) posted a comment (in blog https://piccola-chinita.blogspot.com/2026/01/huh-conversations-02-uk.html) saying he can sometimes guess at the meaning of a Chinese character without knowing its reading. (He's done a bit of basic Chinese.)
In my response to that comment of his, I raised the example of 凹凸 which one doesn't need to know the readings for to get to the meaning.
凹凸不平
āo tū bù píng
"concave convex not level"
It's used for describing a surface that's uneven, especially potholes in the road, which is particularly of concern to cyclists, which Valerio is.