Invulnerable to fear or intimidation:
— Intrepid pioneers.

synonyms: audacious, brave, dauntless, fearless, hardy, unfearing.

Roget 861: courageous, brave; valiant, valorous; gallant, intrepid; spirited, spiritful^†; high-spirited, high-mettled^†; mettlesome, plucky; manly, manful; resolute; stout, stout-hearted; iron-hearted, lion-hearted; heart of oak; Penthesilean.    bold, bold-spirited; daring, audacious; fearless, dauntless, dreadless^†, aweless; undaunted, unappalled, undismayed, unawed, unblanched, unabashed, unalarmed, unflinching, unshrinking^†, unblanching^†, unapprehensive; confident, self-reliant; bold as a lion, bold as brass.    enterprising, adventurous; venturous, venturesome; dashing, chivalrous; soldierly etc. (warlike) 722; heroic.    fierce, savage; pugnacious etc. (bellicose) 720.    strong-minded, hardy, doughty; firm etc. (stable) 150; determined etc. (resolved) 604; dogged, indomitable etc. (persevering) 604.1. up to, up to the scratch; upon one's mettle; reassured etc. v.; unfeared^†, undreaded^†.    ... show more