Harumscarum is an interesting word that means impulsive, reckless and disorganized behaviour. There are a few synonyms that can be used in place of this word. The closest word is 'rash,' which refers to a person acting without thinking through the consequences of their actions. Other synonyms include 'heedless', 'hasty', 'careless', 'thoughtless', and 'impetuous'. These words all share the common thread of impulsive and reckless behaviour. In addition, 'crazy' could also be used in some context as it can refer to a person who behaves in an erratic or unpredictable way. Whatever the context in which it's used, the word 'harumscarum' is a great way to describe a person who lacks direction and acts without thinking.