wimp

noun
  1. A person who is perceived as weak, cowardly, or lacking in courage or determination. noun
    He was called a wimp for not standing up to the bully.
    She didn't want to be seen as a wimp, so she agreed to the challenge.
  2. To act in a weak or cowardly manner; to fail to show courage or determination. verb
    He wimped out of the bungee jump at the last minute.
    Don't wimp out now, we're counting on you to finish the project.