A Pygmy is a member of any human group whose adult males grow to less than 150cm or less than 155cm in average height. Members of a slightly taller group are called pygmoids. Aka,Efe and Mbuti of Central Africa are some of the best known groups.The term "Pygmy" is often considered degrading. Many so called pygmies prefer instead to be referred to by the name of their various ethnic groups,or names for various interrelated groups such as the Aka,Baka,Mbuti and Twa. The term Bayaka, the plural form of the Aka/Yaka, is sometimes used in the Central African Republic to refer to all local Pygmies.