A term sometimes used for a
rate coefficient. For example, if the rate equation is:
the function

is the pseudo first-order
rate constant (or first-order
rate coefficient) with respect to B. Similarly,

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.
Source:
PAC, 1996, 68, 149
(A glossary of terms used in chemical kinetics, including reaction dynamics (IUPAC Recommendations 1996))
on page 178
Cite as:
IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by A. D. McNaught and A.Wilkinson. Blackwell Scientific Publications, Oxford (1997). XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8.
doi:10.1351/goldbook.