The word 桀骜不驯 is formed through the direct combination of four characters: 桀, meaning fierce or unruly; 骜, meaning proud or arrogant; 不, meaning not; and 驯, meaning tame or domesticated. These characters are sequentially placed to create a literal description of something that is fiercely proud and not submissive, resulting in a compound phrase that conveys stubbornness and unruliness.