A term sometimes used for a rate coefficient. For example, if the rate equation is: $$v=k\text{[A]}\text{[B]}$$ the function $k\text{[A]}$ is the pseudo first-order rate constant (or first-order rate coefficient) with respect to B. Similarly, $k\text{[B]}$ is the pseudo first-order rate constant (or first-order rate coefficient) with respect to A. The term pseudo rate constant is particularly useful when the concentration of one reactant is much greater than that of another.