tribal system

the limbic system, the part of the brain involved in our behavioural and emotional responses

immune system

polyandry

central nervous system

outmoded set-up, system or order

economic system

decimal system

system of education or instruction

feudalism, feudal system

(Biology) the natural management of cells

Reproductive system.

solar system

(Biology) nervous system, the mechanism concerned with the correlation and integration of various bodily processes and the reactions and adjustments of the organism to its environment

habit, way of life, disposition, custom, practice, conduct

time table, schedule, line up

Colonial system, colonialism.

nervous system