Nouns

(n)dare, daringa challenge to do something dangerous or foolhardy“he could never refuse a dare”
(n)boldness, daring, hardiness, hardihoodthe trait of being willing to undertake things that involve risk or danger“the proposal required great boldness”, “the plan required great hardiness of heart”

Adjectives

(s)audacious, daring, venturesome, venturousdisposed to venture or take risks“audacious visions of the total conquest of space”, “an audacious interpretation of two Jacobean dramas”, “the most daring of contemporary fiction writers”, “a venturesome investor”, “a venturous spirit”
(s)avant-garde, daringradically new or original“an avant-garde theater piece”