Why is there a random watermark on an xkcd? The original is here, for anyone who wants the alt text: https://xkcd.com/2943/

Søren Sørensen, who came up with the concept of pH, wasn't clear on what the letter "p" meant. It does involve powers of 10 and can be measured using electrical potentials, so the best guesses are "potential" or "power", or several words that mean "power" in other languages and also happen to start with "p". Bottom line, we don't know, and unless somebody discovers more of Sørensen's notes or a way to speak with the dead, we never will.

That's actually an interesting one.

The 'p' could have a different meaning for a variety of languages. 'Puissance' in French, 'Potenz' in German, 'potential' or 'power' in English, 'pondus' or 'potentia' in Latin, or 'Potens' in Danish (probably the Danish one originally, since it was a Danish chemist who first introduced the measurement).

It's very fun that because of the vagueness, various languages can have its meaning directly translated to their own.

Protons. As in protons, How many. On a weird logarithmic scale with 7 in the middle, of course.

Oh we're going to pHight today, is that it?

Easy. Pico Henry. Not sure why chemists are so concerned with such a small amount of magnetism though...

It's power of Hydrogen. We should've been using Watts to measure it this whole time.

PornHub

Phat-ass hydrogen

I was taught potenz in my school textbooks. potenz Hydrogen

Negative log of the concentration of…(Hydrogen ions, in pH).

Potencial de hidrógeno

I don't get what the joke is