There are several synonyms for the phrase "notorious gentleman" that can be used to describe a man with a less than favorable reputation. Some alternatives to "notorious gentleman" include "infamous gentleman," "scandalous man," "disreputable gentleman," "noted rake," and "unscrupulous gentleman." These phrases suggest a man who is known for his mischievous, questionable, or immoral behavior. While they may not always be used in a negative context, they certainly imply that the man in question has a less than honorable reputation. Whether for literary purposes or real-life situations, these synonyms for "notorious gentleman" are certainly valuable additions to any vocabulary.