He never follows the company dress code and is known as a rule-breaker.

rule-breaker 是由名词 rule（规则）和动词 break（打破）加上名词后缀 -er 组成的复合名词。break 表示"打破、违反"，-er 表示"做某事的人"，所以 rule-breaker 指的是"违反规则的人"。