Autonomous consumption is the minimum level of consumption or spending that must take place even if a consumer has no disposable income, such as spending for basic necessities. This contrasts with discretionary consumption, which is used for non-essential items. When combined with discretionary income, a person's autonomous consumption determines his or her real income or real wages.
OR
This is the level of consumption which does not depend on income. The argument is that even with zero income you still need to buy enough food to eat – either through borrowing or running down savings.