The word 追究 (zhuījiū) is a compound verb formed through the combination of two semantically similar characters: 追 (zhuī), meaning "to chase" or "to pursue," and 究 (jiū), meaning "to investigate" or "to examine thoroughly." This type of morphological formation, where two near-synonymous morphemes are joined, is common in Chinese to create a word with a more specific or intensified meaning. In this case, the combination amplifies the sense of a determined inquiry, resulting in the meaning "to investigate thoroughly," "to look into," or "to hold someone accountable," conveying the idea of actively pursuing a matter to its root cause or conclusion.