brave - This means a readiness or willingness to face danger or pain. You can feel fear and still be brave by overcoming that fear. "The little girl was very brave, and did not cry when getting her ears pierced." audacious - This usually implies a lack of respect, in addition to being brave. In fact, you can be audacious without being brave at all, if you simply don't know or don't understand the risks. "The audacious child told his mother that he would drive the car." bold - This usually is much more general than brave. You would not normally use this to describe someone who is facing a specific fear. Someone who is bold usually has confidence that bad things will not happen, rather than a willingness to face those bad things. If you know exactly what dangers are involved in an action, you probably would not use "bold". "Brave" is a little better in this case. "He walked boldly into the room full of strangers." ("Bravely" used here would imply that that there is a good chance the strangers will harm the man in some way, rather than it is simply unknown.) adventurous - This is simply a willingness to try new things. This usually means brave, but not always. Without risk, you can't be brave, but you can be adventurous. However, if something isn't new, it isn't really adventurous. "I am feeling adventurous, so I will try the peanut butter and bananas." daring - This is bravery of an adventurous kind. That is, you are willing to face danger or pain to try new things. "You need to be daring in order to try bungee jumping."

its just synonyms (a word that has same/nearly the same meaning). so basically all the words is actually has the same meaning of fearless/brave.

"Audacious" and "brave" can mean the same thing, but there is a subtle difference. "Brave" can refer to the willingness to risk injury or death. "Audacious" can be used in the same way, but leans more to the willingness to risk failure. An army general may be brave, but not audacious - him might be willing to risk is own life, but not risk defeat of the army he commands.