It stands for product, that is, the output of goods and services, denominated in dollars (current and inflation-adjusted).
It is therefore mystifying to read this, by Arnold Kling:
What is GDP supposed to measure? I think of it as a measure of economic activity, meaning goods and services bought in the market.
The fact that GDP omits the value of home production (cooking, cleaning, lawn-mowing, etc.) means that GDP is an incomplete measure of the total output of goods and services. The remedy for that omission would be to estimate the dollar value of those services if they were purchased at market prices.
Kling tries to get around that objection:
If I pay you to mow my lawn, your labor counts in GDP. If I mow my own lawn, my labor does not count in GDP. That might seem wrong, but I believe it is exactly right. I think of economic activity as specialization and trade. We exploit comparative advantage and the division of labor. The more we outsource, the better off we are….
People who think in terms of production complain that housework belongs in GDP. But I say that if a woman (or a man) engages in housework, that is economic malfunctioning. She should be able to outsource housework to machinery and/or someone she employs.
Economic activity isn’t specialization and trade. It’s the production and consumption of goods and services, however inefficiently. Those that are produced at home (or on the farm) aren’t necessarily inferior to those that are produced by someone else. A lot of people actually enjoy producing and consuming their own goods and services. To them, those goods and services are just as valuable (perhaps more valuable) than the things they could buy from someone else. I am also bothered by the implication that housework has no value unless it’s outsources, which demeans those women (and men) who do their own housework because they can’t afford to outsource it.
Take the case of an apple farmer who reserves a part of his output for consumption in the form of apples (simply eaten), applesauce, apple butter, apple pies and tarts, desserts that include apples and other fruits, etc. If he raises hogs, he probably includes apple peels in their slop. Why should those parts of his apple crop not be counted in GDP just because the farmer uses the apples instead of selling them?
Kling is on the wrong path. He should use his formidable brainpower to think of ways to count home production in GDP so that it better measures what it’s supposed to measure: the total value of things produced in the U.S.