z-distribution: cf. normal distribution.

Zero-based budgeting: budgeting method that starts each year from zero or no activity in each category, and which therefore requires each activity to be justified and costed again each year. układanie budżetu zrównoważonego

Zero-sum budgeting: deficit-neutral budget process in which new expenditures are paid through cuts in existing programmes or increases in revenue; end result is the same bottom line and no increase in the deficit (if governmental) or debt (if referring to private or public corporation or company). układanie budżetu zrównoważonego

Zone of saturation: soil or rock located below the top of the groundwater table; by definition, the zone of saturation is saturated with water; cf. water table. strefa nasycenia/saturacji

Zoonosis: infection or infectious disease transmissible under natural conditions from vertebrate animals to man, e.g. rabies, plague.