Last name Decim (Decima 
, Decim 
) , all over the world, is quite a common surname. The cognomen Decim is habitual in Argentina, where it is quite a common surname, Uruguay, where it is quite a rare surname, and Italy, where it is a rare surname. Measured by absolute frequency, it is commonest in Argentina, Italy, and France. Very seldom, Decim is the forename as well as the last name.