"Un-straps" refers to the action of freeing or releasing something from straps. The antonyms of this word are "straps," "fastens," "secure," and "ties." These words signify the act of constraining or connecting an object with the help of straps, ties, or other fasteners. In various contexts, "straps" can refer to a secure attachment, such as a buckle or latch to keep something in place. Conversely, the term "un-straps" means to remove this secure attachment, undoing the buckle or untying the straps. Therefore, the antonyms of "un-straps" all describe the act of binding or securing.