When something is not held fast, it means it is not secure or stable. There are many synonyms that can be used to describe this state of being. Unfastened, loose, unsecured, untethered, and unanchored all convey the sense that something is not held fast. Similarly, words like unstable, wobbly, shaky, and precarious all describe a lack of security or stability. These words can be used to describe physical objects like furniture or buildings, as well as abstract concepts like relationships or career paths. When something is not held fast, it is important to take steps to secure it or find a more stable solution.