Recorded as Saccu, De Sacco and Sacho, we first see it in 1374, a certain Jacobinus de Sacco, a tax collector. It is prevalent in Kirkop.
It most likely derives from the Italian sacco meaning "bag, sack, pouch, purse" and may relate to a maker or seller of such items. Though less likely, it may have connections to the name Isacco.
The pouch or purse on this coat of arms harkens to its etymological root. The three mullets of six points are a symbol of the Christian faith, further enhanced by the argent (silver/white) field indicating piety, purity and sincerity.