Second order

Second order reactions can be defined as chemical reactions wherein the sum of the exponents in the corresponding rate law of the chemical reaction is equal to two.byjus.com. 
In the discipline of electrical engineering, "A first order control system is defined as a type of control system whose input-output relationship (also known as a transfer function) is a first-order differential equation. A first-order differential equation contains a first-order derivative, but no derivative higher than the first order. The order of a differential equation is the order of the highest order derivative present in the equation. [...] The first order of a system is defined as the first derivative with respect to time and the second-order of the system is the second derivative with respect to time."electrical4u.com.
* Second-order conditioning, a form of learning from previous learning
* Second-order desire, the desire to have a desire for something
* Second-order simulacra, a symbol with no real object to represent
* Second-order stimulus, a visual stimulus distinguished by an aspect other than luminance
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Carcinisation; Level; Stage; Time management; Hierarchy; Order; Layer;
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