Prepensely means intentionally or deliberately. Some antonyms for the word prepensely include accidentally, unintentionally, or involuntarily. These antonyms suggest that there was no conscious effort or plan to carry out a particular action. For example, someone might trip and accidentally knock over a vase, which would be an unintentional act. Similarly, someone might blurt out a secret without meaning to, which would be an involuntary act. The opposite of prepensely suggests that the action was not intended or planned, often resulting in an unintended consequence. While prepensely implies a sense of control or agency over one's actions, its antonyms suggest a sense of happenstance or lack of control.