Wikipedia:
Meat is animal flesh that is used as food.[1] Most often, this means the skeletal muscle and associated fat, but it may also describe other edible tissues such as organs, livers, skin, brains, bone marrow, kidneys or lungs.[1] The word meat is also used by the meat packing and butchering industry in a more restrictive sense?the flesh of mammalian species (pigs, cattle, etc.) raised and prepared for human consumption, to the exclusion of fish, poultry, and eggs.
Makes sense to me. It's like the word "earth". On one hand, it means the planet we are on, but it also specifically means "dirt", as opposed to water, even though most of the planet is covered with water.