Even worse than trying to search for single-letter variables that are defined somewhere in a mathematical text is trying to find the definitions of operators, if all you know is the squiggle used to denote that operator. For example, integrals are denoted by a slide-looking squiggle, so if you see one and don't know it's called an "integral", you can't look up what it means. If you do find a definition, the Wikipedia page you'll get describes integrals as "the signed area of region bound by (the function parameter's) graph", with a full...
Death from old age often involves drowning in the fluid that accumulates in your lungs when you get pneumonia.