I’m wondering if scale, as in the crud that can build up on certain materials under certain conditions, is simply derived from the fish scale sense. It would seem like it, since it’s the ‘shell or husk’ Otherwise, yay, a fourth meaning!
It’s the fish scale meaning. If I could post all of the OED stuff here I would. The sense of flaking from a husk or rind is from the 1450s - onion skin is referenced in this sense. Oxide films like rust date in the 1520s, and scale for tooth tartar is from the 1590s.
I’m wondering if scale, as in the crud that can build up on certain materials under certain conditions, is simply derived from the fish scale sense. It would seem like it, since it’s the ‘shell or husk’ Otherwise, yay, a fourth meaning!
Now what about a music scale?
That’s probably based on the first definition because you can play either an ascending or descending scale.
Also the music staff kinda looks like a ladder.
That is correct. It’s also a very modern sense of the word given the age of the root.
It’s the fish scale meaning. If I could post all of the OED stuff here I would. The sense of flaking from a husk or rind is from the 1450s - onion skin is referenced in this sense. Oxide films like rust date in the 1520s, and scale for tooth tartar is from the 1590s.