ˈzīməjə̇n, -ˌjen noun
( -s )
Etymology: International Scientific Vocabulary zym- + -gen
: an inactive protein precursor (as trypsinogen or pepsinogen) of an enzyme especially a proteolytic enzyme that is secreted in living cells and can be activated by catalysis (as by a kinase or an acid)
zymogen granules
— called also proenzyme