diffident, mousy (or mousey), scary, shy, skittish, timid

anxious, apprehensive, nervous

careful, cautious, heedful, prudent, unadventurous

afraid, agitated, disconcerted, disquieted, disturbed, frightened, horrified, panicked, panic-stricken, perturbed, scared, shocked, spooked, startled, terrified, terrorized, unnerved, upset

appalled, concerned, dismayed, worried

unmanly, weak, wimpy

chicken, chickenhearted, chicken-livered, coward, cowardly, craven, dastardly, fainthearted, fearful, gutless, lily-livered, milk-livered [archaic], nerveless, poltroon, poor-spirited, pusillanimous, spineless, spiritless, timorous, uncourageous, ungallant, unheroic, weakhearted, yellow