The word "Madbrained" is one of those outdated terms that may not find its way into our modern-day conversations. If you're looking for synonyms for this word, some good choices are "reckless," "impetuous," "dizzy," "daring," and "foolhardy." These terms carry the same connotations of being unpredictable and lacking coherent thought. "Impulsive," "headstrong," "unthinking," and "harebrained" are other options to consider. Essentially, anything that suggests a lack of rationality or sound judgment would fit the bill. Remember to only use these words in the right context, as some may be considered rude in certain circumstances.