Anabolic sterois, anabolic-androgenic steroids or AAS, are a class of steroid hormones related to the hormone testosterone. They increase protein synthesis within cells, which results in the buildup of cellular tissue (anabolism), especially in muscles. Anabolic steroids also have androgenic and virilizing properties, including the development and maintenance of masculine characteristics such as the growth of the vocal cords and body hair. The word anabolic comes from the Greek: anabole, "to build up", and the word androgenic comes from the Greek: andros, "man" + genein, "to produce".