The antonyms for the phrase 'most well-regulated' will denote the opposite meaning from a highly regulated thing. The antonyms of well-regulated could be disordered, unregulated, chaotic, unsystematic, or unruly. These words signify a lack of order, control, or coordination. When something is disordered or unsystematic, there is no structure, no methodology and it often leads to confusion. Unregulated or unruly suggests a lack of control, as in a situation or environment where there are no rules or restrictions. Chaos can also describe a state of disorder and confusion where everything is out of control. Thus, these alternate words provide a counterpoint to the idea of something being most well-regulated.