When something increases the same fraction or percentage, rather than the same amount, during each period of time, the numerically savvy call it exponential growth. It would almost certainly be inaccurate for a general counsel to announce that outside counsel spending by her department, for example, has grown exponentially for a period of years. It might have doubled from one year to the next but it is highly unlikely that it doubled once again the next year let alone doubled also in the most recent year. Too many people use “exponential” as an adjective when they really mean “dramatic”.
Had the general counsel’s spend been $1 million in year one, an exponential doubling would see $2 million in year two, $4 million in year three, and $8 million in year four. That level of explosive growth can only happen for a short time and starting from a small base. This comment arose from Samuel Arbesman, The Half-Life of Facts: Why Everything We Know Has an Expiration Date (Current 2012).