Should you purchase your meat from a supermarket, the most commonly used definitions for commercially-packed, USDA-sanctioned meat are:
ORGANIC (USDA): Meat from animals raised from birth on without the use of growth hormones or antibiotics (vitamin and mineral supplements allowed) and fed 100% organic grass or grain. The animals should have open access to pasture and the meat may not be irradiated.
NATURAL: Minimal processing of and no artificial additives administered to the meat. Many producers use their own definition which, in some cases, indicates that, from birth on, neither antibiotics nor growth hormones were used on the animals or in their feed. If pre-packaged, the label will so designate.
RAISED WITHOUT ANTIBIOTICS: Simply that, the animal has not received any antibiotics. This does not indicate any of the other conditions of production.
NO HORMONES ADMINISTERED: Simply that, the animal has not received any growth hormones, either through injection or in the feed. This does not indicate any of the other conditions of production.
100% GRASS-FED AND PASTURED: This simply indicates that the animal solely fed on pasture and grass. This does not indicate any of the other conditions of production, including the circumstances of their feeding.