The surname Arnow is derived from a proud symbol of ancient Jewish culture. Before the late Middle Ages, people were known only by a single name. However, as the population increased and travelers set out on their journeys, it became necessary for people to adopt a second name to identify themselves. Jewish hereditary surnames were adopted from a variety of different sources. Two of the most common types of Jewish family names are patronymic surnames, which are derived from the father's given name, and metronymic surnames, which are derived from the mother's given name. The surname Arnow is a patronymic surname, which comes from the Hebrew given name Aharon. Traditionally, this surname is believed to have derived from the Hebrew word har-on, which means mountain of strength.