Here are some examples:
* Unhappy: Not happy
* Unbelievable: Not believable
* Uncertain: Not certain
* Unfair: Opposite of fair
* Unstable: Lack of stability
* Unpack: To remove things from a container
* Undress: To remove clothes
It's important to note that "UN" can sometimes have a slightly different meaning depending on the word it's attached to. For example, "undo" doesn't mean "not do," but rather "reverse the action of doing."