"Fat Free"

"Fat Free" has slightly different legal definitions depending upon the type of food but generally means that the food has

 less than 0.5 grams of fat per "RACC" (Reference Amounts Customarily Consumed)--basically a serving.

Terms that mean the same thing: 
"Zero fat"
"No fat"
"Without fat" 
"Trivial Source of fat" 
"Negligible Source of fat" 
"Dietarily Insignificant Source of fat"