Hi Doctormatt perhaps we could say that a derivative is the rate of change of a function or quantity at a certain time That seems fairly unequivocal and much more accessible than what is currently there I m not so much a proponent of my own version so much as an opponent of the use of the meaningless to the non mathematical word instantaneous I don t really mind the differentiation thing being right after the initial sentence because people might have clicked on the derivative page after going to differentiation a disambig page It s certainly grammatical to say Finding a derivative is called differentiation see gerund However now that I think about it maybe we should just say Differentiation is the process of finding a derivative We put the sentence in the active voice Your thoughts Best