Crossing one's mind denotes that something has briefly occurred in one's thoughts or imagination. However, there are many antonyms to describe the opposite of having a thought come to mind. These could include words such as oblivious, forgetful, distracted, unthinking, vacant and absent-minded. Each of these antonyms have their own distinctions in meaning, but combined, they all describe a state of being where one's mind is not actively engaged in processing ideas or concepts. While crossing one's mind suggests a momentary consideration, the antonyms highlight the opposite of being absent or unfocused.
