boldest achievement

[hhtt21]

1.This is the story of man's boldest achievement.

Does bold used above mean this:

fearless before danger

https://www.merriam-webster.com/dictionary/bold

Are 2 and 3 identical in meaning with 1?

2. This is the story of man's bravest achievement.
3. This is the story o man's most intrepid story.

http://www.goodreads.com/book/show/3389563-we-reach-the-moon

Thank you.

 

[GoesStation]

I didn't watch much of it, but this video looks like it might offer some really helpful tips. Pay particular attention to places where the presenter discusses how not​ to use a dictionary.
[video]https://www.engvid.com/when-and-how-to-use-a-dictionary/[/video]

 

[hhtt21]

Will you ​please stop trying to shoehorn the meaning of a word into the definitions given in a dictionary or two.

How should words be learnt?

Thank you.