Ó hArgadáin
Ó hARGADÁIN—I—O Hargedaine, O Hardagane, O Hargedan, Hargaden, Hargadon, (Hardiman, Harman, Harmon); 'descendant of Argadán' or 'Airgeadán' (diminutive of airgead, silver, hence white, shining); also Ó hAirgeadáin; a Connacht surname; now often, but incorrectly, anglicised Hardiman, Harman, &c.
Alphabetical Index to Irish Surnames