The term 'small mass' can be broken down into four crossword solutions: WAD (3 letters), PAT (3 letters), LUMP (4 letters), and GRAM (4 letters). WAD is a small bundle of something, usually paper or cloth. PAT is a light tap or stroke, often used to describe the motion of a hand. LUMP is a small, solid mass of something, such as a piece of coal or sugar. Finally, GRAM is a unit of mass in the metric system, equal to one thousandth of a kilogram.