GUINNESS Family History
This name, with variant spelling MacGenis, McGinnis, MaGennis, Guin(n)ess etc., is an anglicized form of the Olde Gaelic (Scots and Irish) 'MagAonghusa'. The Gaelic prefix 'mac' (frequently written as 'mag' before a vowel) indicates 'son of'. Aonghusa is the genitive form of the male given name Aonghus meaning 'Unique Choice' from 'aon', one plus 'gus', choice or enterprise. The first bearer of the name is believed to be Aonghus Turimleach, one of three Irish brothers, who invaded Scotland in the 3rd Century B.C., and gave his name to the district of Angus.