Of problematic origin. The name seems to have been first used in Spain and Portugal, and, according to tradition, was the name of the wife of St Paulinus of Nola, who spent most of his life in Spain; she was said to have originated (and to have derived her name) from the Greek island of Thēra. However, this story is neither factually nor etymologically confirmed.
Italian: patronymic from a short form of the medieval personal name Ademaro, Adimaro, derived from a Germanic personal name composed of the elements adal ‘noble’ + mari, meri ‘famous’. In southern Italy, it is more often from a short form of Amari, or a nickname from amaro, amaru, also maru ‘unlucky’.