The crossword solution for the term SUFFIX FOR BILLION is AIRE, which is a four-letter word. AIRE is a suffix that is used to denote a billion in the International System of Units (SI). It is derived from the French word 'BI' meaning two and 'illion' meaning a million, thus making it a combination of two words. AIRE is used to represent a billion in the SI system, which is equal to one thousand million or 1, 000, 000, 000.