The letter ℘: name and origin? (2017)

I left college with a math degree and a profound antipathy for weird cursive symbols. The one that nearly killed me was the Greek "xi". I couldn't pronounce it, and I couldn't write it with any fluency, and in some of the classes I took it was everywhere.

I encounter ξ (xi), and also ζ (zeta) a lot. Honestly, when I write them out by hand, I just make a "wild squiggly line" for ξ and a "simplified squiggly line" for ζ.

If I write it out by hand, it's most likely just for my eyes anyway, and I'd type it out on a computer if I'd want others to have a look at it. But even if I gave someone else my handwritten note, I think from context it would be pretty clear what the "squiggly lines" are supposed to be.