"Careless abandon" is a phrase that usually connotes reckless behavior and acting without any concern for potential consequences. Some synonyms for this phrase include recklessness, heedlessness, thoughtlessness, impulsiveness, and abandon. The above words indicate a disregard for potential outcomes or the safety of oneself and others. Another phrase that can be used to replace "careless abandon" is "rash behavior," which suggests impulsivity and an absence of restraint. The use of such words and phrases may be deemed appropriate for scripts, novels, or character descriptions. However, it is always essential to double-check their usage when implementing them in professional or formal documents, conversations, or narratives.