How would the author define adventure?

I’m certainly not a writer like Mark Twain (I wish!) but there are certain common traits to his adventures. They tend to be very organic. Twain forgoes complexity for simplicity. His major character's of Huck and Tom posses a certain authenticity. They live for the moment and the direct experience of life. Along the way they also develop their own moral value system separate from the agreed upon precepts of society which tended to be hypocritical. The protagonists always maintain their boyish charm in the midst of danger and excitement.