What effect does adding the prefix un have on a word?

Adding the prefix "un" to a word typically has the effect of reversing or negating the meaning of the original word. It creates the opposite of the original word.

Here are some examples:

* Happy becomes Unhappy

* Locked becomes Unlocked

* Tied becomes Untied

* Real becomes Unreal

* Important becomes Unimportant

The prefix "un" is often used to create antonyms (words with opposite meanings). However, there are some exceptions where "un" might not create a perfect opposite, or it might have a different meaning altogether.

For example, "unwell" doesn't mean the opposite of "well"; it means "sick." "Unnatural" can sometimes mean "uncommon" rather than the opposite of "natural." It's always good to check a dictionary to be sure of the specific meaning of a word with the "un" prefix.