irrepressible, indefatigable, redoubtable, steely, fearless, doughty, implacable, feisty, tenacious, unconquerable, imperious, ferocious, fearsome, resolute, formidable, plucky, unyielding, admirable, stoic, dauntless, courageous, gallant, uncomplaining, ageless, saintly, unbending, stouthearted, tireless, brutish, unflappable, stoical, valiant, heroic, peerless, unflagging, ruthless, spunky, unflinching, pugnacious, indestructible, inimitable, headstrong, resourceful, wily, domineering, stolid, impish, unwavering, irascible, superhuman, charismatic, imperturbable, immortal, tigerish, uncompromising, cunning, unstoppable, rumbustious, stubborn, undying, unfaltering, endearing, stalwart, vivacious, industrious, beastly, perseverant, unshakable, effervescent, leonine, unerring, mulish, enigmatic, diminutive, grit, unshakeable, flinty, stakhanovite, unswerving, obdurate, obstinate, unvanquished, gutsy, eloquent, selfless, archetypal, untiring, relentless, saintlike, unregenerate, nonpareil, mighty, merciless, undiminished, untamable, hardbitten, maniacal, spritely, coltish, machinelike, adamantine, uncanny, aeroplane, affaire, aurora, austen, barrow, bluntness, bravery, callousness, caves, codex, complacency, concession, coolness, documentary, duo, firmness, foree, fortitude, generalship, genius, undaunted, invincible, dogged, intrepid, persevering, steadfast, virile, brave

never-say-die, unsubduable