Once over refers to a quick inspection or review of something. Its antonyms include a thorough examination, a detailed analysis, or a comprehensive study. While a once over connotes a brief, casual look at something, its antonyms suggest a more detailed and rigorous examination. For example, while a health professional might give a patient a once over during a routine check-up, they would likely conduct a thorough examination if the patient was experiencing symptoms of an illness. Similarly, a manager might give a once over to a report submitted by an employee, but may conduct a more detailed analysis if the report is critical or important.