21 CFR §158.3

1. (a)Lot. A collection of primary containers or units of the same size, type and style manufactured or packed under similar conditions and handled as a single unit of trade.
2. (b)Lot size. The number of primary containers or units (pounds when in bulk) in the lot.
3. (c)Sample size. The total number of sample units drawn for examination from a lot.
4. (d)Sample unit. A container, a portion of the contents of a container, or a composite mixture of product from small containers that is sufficient for the examination or testing as a single unit.
5. (e)Defective. Any sample unit shall be regarded as defective when the sample unit does not meet the criteria set forth in the standards.
6. (f)Acceptance number. The maximum number of defective sample units permitted in the sample in order to consider the lot as meeting the specified requirements. The following acceptance numbers shall apply:
7. (g)Acceptable quality level (AQL). The maximum percent of defective sample units permitted in a lot that will be accepted approximately 95 percent of the time.