chicken, chicken-livered, chickenhearted, cowardly, craven, dastardly, lily-livered, milk-livered(archaic), poltroon, pusillanimous, recreant, spineless, unheroic, yellow

diffident, fainthearted, fearful, timid, timorousafraid, frightened, scaredcareful, cautious, warybashful, coy, shyfeeble, soft, unmanly, weak

brave, courageous, daring, dauntless, doughty, fearless, gallant, greathearted, gutsy, hardy, heroic(also heroical), intrepid, lionhearted, stalwart, stout, stouthearted, valiant, valorous

audacious, bold, brazen, cheeky, nervyplucky, spirited, spunkydetermined, resolute