adj. 25B6; adjective INVINCIBLE, unconquerable, unbeatable, unassailable, invulnerable, unshakeable; indefatigable, unyielding, unbending, stalwart, stout-hearted, lionhearted, strong-willed, strong-minded, steadfast, staunch, resolute, firm, determined, intransigent, inflexible, adamant; unflinching, courageous, brave, valiant, heroic, intrepid, fearless, plucky, mettlesome, gritty, steely.
submissive.