Total Fertility Rate (TFR)
A measure of the average number of children a typical woman will have as she passes through her reproductive life.

Replacement Level Fertility
The Total Fertility Rate is roughly 2.1 births per woman for most industrialized countries but ranges from 2.5 to 3.3 in developing countries because of higher mortality rates. Taken globally, the total fertility rate at replacement is 2.33 children per woman. At this rate, global population growth would trend towards zero.

Steady State Economy
A prosperous and dynamic economy that does not need to grow phsyically in order to develop,  featuring stabilized population and consumption.  Such stability means that the amounts of resource throughput and waste disposal remain roughly constant.  The key features of a steady state economy are:

• Sustainable scale, in which economic activities fit within the capacity provided by ecosystems.
• Fair distribution of wealth.
• Efficient allocation of resources.