What is a small sin or fault commonly referred to as?

The term "peccadillo" specifically refers to a minor sin or fault, often used in a context where it denotes a slight deviation from the expected norms of behavior. This word originates from the Spanish "pecadillo," which is a diminutive form of "pecado," meaning sin. It conveys the idea of a trivial misdemeanor rather than a serious wrongdoing, often highlighting the somewhat lenient view that society may take towards such small indiscretions. The use of "peccadillo" suggests that the behavior in question is more forgivable and not deserving of harsh judgment, capturing the nuance of human imperfection in a sympathetic light.

The other terms do not convey this specific meaning: "pithy" refers to being concise and meaningful, "pluck" signifies courage or determination, and "pomp" relates to ceremonial or ostentatious display. Hence, "peccadillo" stands out as the correct answer for identifying a small sin or fault.