The phrase "mark against one" commonly refers to a negative point or strike against someone, often in the context of a judgment or assessment. Some synonyms that can be used instead of "mark against one" include demerit, black mark, blemish, stain, or blot. These words all suggest a negative mark or impression that could harm one's reputation or standing. Other possible alternatives include criticism, fault, flaw, weakness, or disadvantage. When communicating about someone's performance or behavior, it's important to choose the right words that accurately convey the intended meaning and tone, without being needlessly harsh or critical.