The term 'MASS OF SMALL BUBBLES' can be described by two crossword solutions: FOAM (4 letters) and FROTH (5 letters). FOAM is a collection of many small bubbles that are held together by surface tension. It is usually created when air or gas is mixed with a liquid. FROTH is similar to FOAM, but it is usually created when a liquid is agitated, such as when it is stirred or shaken. FROTH is usually made up of smaller bubbles than FOAM.