Without forethought means to act or speak impulsively, without considering the consequences. Synonyms for the phrase include impromptu, spontaneous, unplanned, off-the-cuff, rash, hasty, unthinking, and unrehearsed. These words emphasize the idea of doing something without premeditation or preparation, often leading to negative outcomes. Other phrases that convey the same idea include on the spur of the moment, without consideration, in the heat of the moment, off the top of one's head, and ad hoc. While sometimes acting without forethought can lead to positive outcomes, it is important to weigh the potential consequences of one's actions before taking them.