This term means that a product contains no amount of, or only trivial or "physiologically inconsequential" amounts of, one or more of these components: fat, saturated fat, cholesterol, sodium, sugars, and calories. For example, "calorie free" means fewer than 5 calories per serving and "sugar free" and "fat free" both mean less than 0.5 g per serving. Examples of synonyms for "free" include "without," "no" and "zero." A synonym for fat-free milk is "skim."
Source: Excerpted from FDA Backgrounder, May 1999: The Food Label.