The antonym for the word "un-destroyable" is "destroyable." The term refers to something that can be destroyed or damaged easily. For instance, a fragile object is not un-destroyable, but instead, it is destroyable. The opposite of un-destroyable can also be fragile, vulnerable, or weak, and this implies that anything that can be destroyed, ruined or broken falls under the category of destroyable. In summary, the antonym for un-destroyable has various synonyms, and anyone can apply them depending on the context of a particular situation.