What is what does the prefix dis mean?

The prefix "dis" means not or opposite of something. It is commonly used to change the meaning of a word to the negative or opposite form. For example, the word "appear" means to be seen or noticed but when the prefix "dis" is added to it, it becomes "disappear", which means to cease to be seen or vanish. Another example is the word "connect" which means to join together, but when the prefix "dis" is added, it becomes "disconnect", which means to separate or break the connection.