If you're looking for a word that is steadfast, determined and unyielding, then you may want to consider "doughty." This word has a few meanings, but the one you're likely to use most is having the strength, courage and resolve to hold on to what you believe in, despite opposition. It's often used in the context of mental toughness, physical stamina and emotional resilience. So if you need a word that encapsulates those qualities, doughty is the perfect word for you.