Morgan discovered that a descriptive term in one society can become a classificatory term in another society. For example, in some societies, one would refer to many different people as "mother" (the woman who gave birth to oneself, as well as her sister and husband's sister, and also one's father's sister). Moreover, some societies do not group together relatives which the English-speaking societies classify together. For example, some languages have no one-word equivalent to "cousin", because different terms refer to one's mother's sister's children and to one's father's sister's children.