Which word best fits the definition of 'to grow quickly and abundantly'?

The word that best fits the definition of "to grow quickly and abundantly" is "burgeon." This term conveys a sense of rapid and vigorous growth, often used to describe things like plants that flourish in ideal conditions or ideas and trends that gain momentum swiftly. In essence, when something is said to burgeon, it implies not just growth, but a flourishing or thriving process, making it particularly well-suited to the definition provided.

In contrast, the other options do not align with the idea of quickly growing in abundance. "Stagnate" refers to a lack of growth or progress, meaning that something is not moving or developing. "Burrow" describes the act of digging or tunneling, which does not imply any growth as per the definition. Lastly, "flatten" suggests a reduction or decrease in height or volume, again opposite to the concept of growth. Thus, "burgeon" stands out clearly as the word that captures the essence of rapid and abundant growth.