The antonyms for the word "un-bolting" include "bolting" and "fastening". When we un-bolt something, we loosen or remove bolts that were previously in place. Therefore, the opposite action is to add or tighten bolts, which is referred to as "bolting". On the other hand, "fastening" implies the action of securing or holding something in place. Rather than specifically using bolts, it may involve using other methods such as nails, screws, or adhesive to hold an object firmly in place. Therefore, the antonyms for "un-bolting" depend on the context and situation in which the term is used.