Blot on the escutcheon is an idiomatic expression that refers to a stain or mark on one's reputation or a blemish on the family's honor. It has its origins in heraldry, where an escutcheon is a shield or coat of arms. The term "blot" usually refers to something negative or shameful, and it can be used to describe a multitude of situations. Synonyms for blot on the escutcheon include black mark, disgrace, shame, flaw, imperfection, stain, smirch, and taint. These words can be used interchangeably in a sentence, but each one emphasizes a different aspect of the mark or stain on one's reputation or character.