The antonyms of 'more undeterred' are 'deterred', 'discouraged', 'disheartened', 'dispirited' and 'frightened'. The person who is undeterred is fearless and determined in his actions, whereas the opposite is deterred, which means to be discouraged, to feel disheartened or dispirited. The word deterred means to hinder, discourage, or restrain someone from doing something. A person may become deterred when faced with challenging obstacles or a lack of confidence. Therefore, it is essential to remember that undeterred means unwavering, reinforcing self-motivation, and staying confident in one's abilities.