The term 'grow rapidly' can be described by a variety of words, such as PROLIFERATE (11 letters), MUSHROOM (8 letters), BURGEON (7 letters), SNOWBALL (8 letters), SPROUT (6 letters), shootup (7 letters), ESCALATE (8 letters), and sproutup (8 letters). Each of these words implies a rapid increase in size or number, often in a short period of time. For example, PROLIFERATE means to reproduce or increase rapidly, while MUSHROOM suggests a sudden growth in size. Similarly, BURGEON implies a sudden and vigorous growth, and SNOWBALL suggests an increase in size or intensity that builds upon itself. SPROUT and shootup both suggest a sudden and rapid growth, while ESCALATE implies a gradual but steady increase in intensity. Finally, sproutup suggests a sudden and rapid growth from a small beginning.