Names for levels of calculus Differentiation can be said to take an expression to a higher order derivative. It seems that different variables inhabit different 'levels' of calculus, some from different areas seem analogous to each other in a way that I am searching for a word for. For example between electrical and mechanical: 1) Charge and displacement 2) Current and velocity 3) Potential difference and force What is the name for the numbers on the left of the list: 'order', 'level'? I haven't found the subject addressed directly anywhere.

When we deal with derivatives and others releted topic as for example **differential equations** or Taylor's expansion we use the term " **order** ".