Derring-do is a word that is used to describe brave and daring actions. There are many words that are synonymous with this phrase, including valiant, heroic, gallant, intrepid, bold, audacious, fearless, adventurous, and daring. These words all convey a sense of bravery and courage, and they can be used to describe a variety of actions, from daring rescues to bold feats of strength. Whether you are describing a brave soldier or a fearless adventurer, these words will help you capture the spirit of derring-do and convey a sense of heroism and courage to your readers.