The word "一个个" is formed through the reduplication of the basic, generic measure word "个" (gè), which is prefixed with the numeral "一" (yī, meaning "one"). This structure follows the common Chinese grammatical pattern of "Numeral + Reduplicated Measure Word" (e.g., 一个个, 一件件). In this specific case, the reduplication of "个" transforms the meaning from simply "one" or "a single" item into an expressive plural that emphasizes a sequential, one-by-one, or distributive action, often translating to "one after another," "each and every one," or "individually" when describing how a action applies to multiple, discrete items within a group.