English form of Hermann, from a Germanic personal name derived from heri, hari ‘army’ + man ‘man’. The name was in use among the Normans and was borne by many immigrants from the Low Countries in the 15th century. Perhaps because of that it continued in occasional use well into the 1700s. It was revived more generally in Britain in the 19th century, when it also became common in America, most probably as a result of the influence of German immigrants.
Spanish, Catalan, and Jewish (Sephardic): habitational name from any of numerous places called Aguilar, from Latin aquilare ‘haunt of eagles’ (a derivative of aquila ‘eagle’), for example Aguilar de Campo in Palencia, Aguilar de la Frontera in Córdoba, and Aguilar de Segarra in Catalonia.