1. a person's name, or a mark representing it, as signed personally or by deputy, as in subscribing a letter or other document. 2. the act of signing a document. 3. Music. a sign or set of signs at the beginning of a staff to indicate the key or the time of a piece.
MAC Pigments. Contrary to popular belief, makeup does expire. MAC cosmetics are no exception. The majority of cosmetics expire in one year. However, there are certain cosmetics that expire in a few short months and certain cosmetics that last a lot longer than one year. The reason cosmetics have expiration dates is because over time bacteria builds up in them and when used they can cause infections, acne, and other nasty afflictions.
Sunscreen, for example, should be tossed one year after being opened. Emulsifiers can even cause some moisturizers to separate. So, check out the ingredients. Generally, prescription products are safe to use after their expiration date, but it will depend on how long the product has been expired. A few months is better than a few years.