The phrase "gutless wonder" is a derogatory term used to describe someone who lacks courage or backbone. However, there are other synonyms that also convey a similar meaning. For instance, the phrase "spineless coward" is commonly used to describe someone who lacks bravery. Similarly, the phrase "chicken-hearted" refers to someone who is easily scared or intimidated. Other phrases like "timid mouse" and "meek milquetoast" also convey a similar message. In essence, all these synonyms depict a character who lacks the courage to confront difficult situations and often succumbs to fear, making them less admirable in the eyes of others.