Being fastened refers to the act of securing or attaching something firmly. Antonyms for this phrase include "being unfastened," "being detached," "being disengaged," "being undone," "being liberated," and "being released." These antonyms imply a sense of freedom, flexibility, or disconnection from something concrete. Being unfastened refers to the act of loosening or undoing something that was previously secure. Being detached implies a sense of removing or separating oneself from something. Being disengage, undo, or liberated implies freedom and release from an attachment. The antonyms for being fastened can have both positive and negative connotations depending on the context in which they are used.