The word 鲁莽 is formed through the combination of two synonymous or semantically reinforcing characters, 鲁 (lǔ) and 莽 (mǎng), to create a single, more expressive disyllabic term. 鲁 originally implied crudeness or rashness, often associated with the blunt character of the ancient Lu state, while 莽 directly denotes recklessness and impetuousness, like wild, overgrown grass. When compounded, their meanings merge and intensify to describe a specific kind of thoughtless, rash, and impulsive behavior, exemplifying a common pattern in Chinese where two characters with similar connotations are paired to solidify an abstract concept.