authority, correction, Irish smachd, Old Irish smacht, Middle Irish smachtaigim, I enjoin, smacht, fine for breaking the law: *smaktu-, from s-mag, root mag, Indo-European magh, be strong; English may, Gothic magan, be able; Greek $$Gmc$$nhos, means (see mac).
Etymological dictionary of the Gaelic language.
Alexander Gairm Publications.
1982.