It is difficult without more context but I am guessing that it refers to Perpendicular Height.
Chat with our AI personalities
It means that its an Acid. pH < 7 is acidic. pH > 7 is basic. pH = 7 is neutral.
math is a really fun thing to do
Crossing, the same meaning that it has generally.
I don't know about math, but in physics and chemistry its a deciliter
Math comes from the Greek language, meaning learning or science.