Not fastened is the opposite of secured or attached. It implies that something is loose or unattached. Other antonyms for not fastened include unfastened, undone, unhooked, unbuckled, unzipped, and open. These antonyms are commonly used when referring to items such as belts, buckles, zippers, and latches. For example, an unfastened seatbelt can result in serious injuries during an accident. In addition to physical objects, not fastened can also refer to concepts or ideas. For instance, a team that is not fastened and lacks cohesion may struggle to achieve its goals. Understanding the antonyms for not fastened is essential for effective communication and ensuring the safety of individuals.