Updated March 26, 2024 Share: Table of contents Boy name origins & meanings Irish : Surname How Popular Is The Name Hennessy Family name origins & meanings Irish : reduced form of O’Hennessy, an Anglicized form of Gaelic Ó hAonghusa ‘descendant of Aonghus’ (see Angus, and compare McGinnis). Appears on 75 Baby Names Inspired by Alcohol, Cocktails, and Spirits