From Longman Dictionary of Contemporary Englishfamiliarlyfa‧mil‧i‧ar‧ly /fəˈmɪliəli $ -liərli/ adverbFRIENDLYin an informal or friendly way
Charles, familiarly known as CharlieExamples from the Corpusfamiliarly• That might seem to be precisely the sort of querulousargument which the Left has familiarly been scorned for posing.• The FBI is looking for Tom Charles, familiarly known as Charlie the Kid.